Milled Submicron Organic Biocides With Narrow Particle Size Distribution, and Uses Thereof

ABSTRACT

A method of milling substantially insoluble solid organic biocides to form a micron or sub-micron product having a narrow particle size distribution is presented. The milling involves wet milling of the organic biocide with high density milling media having a diameter between 0.1 mm and 0.8 mm, preferably between 0.2 mm and 0.7 mm, and a density equal to or greater than 3.8 g/cc, preferably greater than 5.5 g/cc, in a ball mill using between about 40% and 80% loading of the mill volume with milling media, and having the organic biocide suspended in an aqueous milling liquid which comprises one or more surface active agents. The milling speed is preferably high, for example from about 1000 rpm to about 4000 rpm. The milled product can be used in foliar applications at a lower effective dosage than prior art formulations, can be used in improved antifouling paint formulations, and can be used in new applications such as the direct injection of solid organic biocide particulates in wood to act as a long lasting wood preservative.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. patent application Ser. No.10/961,157, filed Oct. 12, 2004, which claims the benefit of U.S.Provisional Application No. 60/616,646, filed Oct. 8, 2004, both ofwhich are herein incorporated by reference in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

not applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

not applicable

SEQUENCE LISTING

not applicable

FIELD OF THE INVENTION

The present invention relates to a method of producing submicron-sizedorganic biocide particles, methods of packaging same, and uses thereof.More particularly, the invention relates to use of high density millingmedia having a diameter between 0.1 and 0.8 mm to provide unexpectedparticle size reduction and narrow particle size distribution even fororganic biocides known to be difficult to mill. This milled organicbiocidal product is therefore useful in particulate form for directinjection into wood, for use in non-fouling paints, and for use infoliar applications at a reduced treatment quantity than was useful forprior art formulations.

BACKGROUND OF THE INVENTION

The efficient use of organic pesticides is often restricted by theirinherent poor water-solubility.

Generally, these water-insoluble organic pesticides can be applied to asite or substrate in three ways: 1) as a dust, 2) as a solution in anorganic solvent or a combination of water and one or more organicsolvents, or 3) as an emulsion that is prepared by dissolving theproduct in an organic solvent, then dispersing the solution in water.All of these approaches have drawbacks. Application of a dust isassociated with drift, poses a health hazard, and is inefficient.Solutions and emulsions that require an organic solvent are undesirable,since the solvent serves no other purpose but to act as a carrier forthe product. As such, the solvent adds an unnecessary cost to theformulation and is an added health risk. Finally emulsions are generallyunstable and must be prepared at point of use, typically in the hours orminutes before use, and minor changes in the formulation, for example byaddition of another biocide, may cause the emulsion to break andseparate.

The low water solubility is also a factor at point of use. Generally,for low solubility fungicides, the amount of a fungicide needed toprotect against various pests is generally dependent on the number ofparticles in a unit area. If 100 particles are needed on a leaf, and ifthe particle diameter is reduced to one third of the former diameter,then the dosage can theoretically be reduced to about 11% of the formerdosage while still maintaining 100 particles on the leaf, resulting inlower cost, less pesticide residue on harvested crops, and mitigation ofenvironmental impact.

It is known to mill certain organic pesticides. For instance, publishedU.S. Patent Application No. 2001/0051175 A1 describes milling largeclasses of fungicides with grinding media of substantially spheroidalshaped particles having an average size of less than 3 mm, and teachesthat “suitable media material include[s] ZrO stabilized with magnesia,zirconium silicate, glass, stainless steel, polymeric beads, alumina,and titania, although the nature of the material is not believed to becritical.” The Examples used ⅛″ steel balls as grinding media, which wasindeed able to reduce the mean particle size of some organic pesticidesbelow 1 micron. We believe these inventors were incorrect in theirassumption that the composition and size of the grinding material wereof little importance.

On the other hand, when a breakthrough is made, the product can be verysuccessful. Copper (on a copper metal basis) is generally used as abiocidal agent (depending on crop, application, and activity) atapplication rates of 0.24 lb to 7.5 lbs per acre. Another biocide iscopper hydroxide, which is a preferred low solubility copper salt, andwhich has >60% by weight copper and a solubility product constant ofabout 2×10⁻²⁰. Several years ago, copper hydroxide used for foliarapplications had a particle size of about 1 to 3 microns. Then, a newproduct Champ DP®, commercially available from Nufarm Americas, was madeavailable with a median particle size of about 0.2 microns. This productwas useful at half the application rate on a variety of crops, and theduration of treatment was of appreciably different than that of theproducts containing larger particles.

This is not to say that all biocides, even all low solubilityfungicides, benefit from smaller size. For example, the ubiquitouselemental sulfur is generally advantageously 3 to 5 microns in diameterwhen used in foliar applications. While smaller particles can be formed,the actions of the atmosphere, moisture, and sunlight combine toeliminate the efficacy of the sulfur particles in too short a time to beof commercial interest. Additionally, particle size reduction belowcertain values (which depend on the product characteristics) can in thepast only be achieved through expensive and elaborate procedures, andsuch procedures quickly price the product out of the market.

Chlorothalonil is commercially available as a suspension having anaverage particle size diameter between about 2 and about 5 microns. Itis known to mill chlorothalonil, but no milling process had everachieved a reduction in the d₅₀ (the volume average diameter) belowabout 2 microns. Backman et al. found that, within the limits tested,the efficacy of Chlorothalonil tended to increase with decreasingparticle size and with increasing milling. Backman's data generally showthat the efficacy of the treatment generally increased with wet millingover air milling, and that the efficacy increased with milling time forthe lowest treatment rate, though the data was not conclusive as theefficacy went down with increased milling time at the two highertreatment rates. See Backman, P. A., Munger, G. D., and Marks, A. F.,The Effects of Particle Size and Distribution on Performance of theFungicide Chlorothalonil, Phytopathology, Vol. 66, pages 1242-1245(1976).

U.S. Pat. No. 5,360,783, the disclosure of which is incorporated hereinby reference, particularly noting the milling method and the dispersantsand stabilizers disclosed therein, discloses in Example 2 milling Manebwith 2 mm glass beads. The resulting mean particle diameter of the Manebwas 1.7 to 1.8 microns. Also in this patent, chlorothalonil (Daconil)was milled in the same manner in Test 5, and the resulting averageparticle size diameter was 2.3 microns.

U.S. Pat. No. 5,667,795, the disclosure of which is incorporated hereinbe reference, particularly relating to the adjuvants, describes milling40% chlorothalonil, 5.6% zinc oxide, a variety of dispersants andstabilizers, and balance water in a wet mill or high speed media mill.This patent does not describe the milling media, but states the averageparticle size of the product was 3 microns.

Curry et al. at International Specialty Products have ground a fewbiocides with 0.1 cm zirconia at 70% to 80% loading. For instance, U.S.Published Patent Application Nos. 2004/0063847 A1 and 2003/0040569 A1describe milling metaldehyde with a variety of surfactants anddispersants, milling at 0-5° C., and recycling the material at 19 passesper minute for 10 minutes. Fine suspensions were produced with particlesize distributions in which 90% of the metaldehyde particles had adiameter less than 2.5 microns, and in which the mean volume diameterwas less than 1.5 microns. A chlorothalonil suspension was described asbeing milled in the same manner, but data on particle size was notreported. However, commonly-assigned U.S. Published Patent ApplicationNo. 2004/0024099 A1 described an example where a composition ofchlorothalonil was wet milled under the same conditions described above,i.e., a 70% to 80% loading of 0.1 cm zirconium (sp) beads at 3000 rpmfor 10 minutes with 19 recycles per minute. The resulting compositionscontained 41% chlorothalonil and a variety of surfactants anddispersants. The milling temperature jacket was 0° C., and thetemperature of the milled material was 15-21° C. The publication claimsthat 90% of the number of particles had a size below 0.5 microns butthat the mean volume diameter (d₅₀) was “less than 3 microns”, meaninghalf the volume of particles had particle sizes greater than “less than3 microns.” The art uses the term “less than” to denote the maximum meandiameter in a series of tests, but it is well known in the art thatroutine changes in parameters such as milling time will not appreciablychange the mean volume (or weight) diameter, as discussed infra. Theresulting chlorothalonil material made according to the InternationalSpecialty Products process thus has a mean volume diameter d₅₀ of 2 to 3microns. This is consistent with the other disclosures.

The phenomena of a wide particle size distribution should be clarified.The International Specialty Products inventors described theirchlorothalonil composition as having 90% of particles below 0.5 microns,but as having a mean volume diameter in the range of 2-3 microns. Thiswide particle size distribution is common, and it severely limits thebenefits of the low particle size product, e.g., when used in paints,wood preservatives, and foliar applications.

For example, in co-pending and commonly-owned U.S. patent applicationSer. No. 10/868,967 filed Jun. 17, 2004, we discussed how particles upto 0.5 microns in diameter were injectable into wood. The mean volumediameter of Champ DP®, a small diameter copper salt product, was about0.2 microns. Therefore, one might expect this material to be readilyinjectable into wood. However, while 57% by weight of particles ofcopper hydroxide in a particular lot of Champ DP® was 0.2 microns orsmaller, when we tried to inject this material into wood this Champ DP®material plugged the surface of the wood and would not penetrate intothe wood matrix. We discovered the reason was that there was a criticalfraction of particles having a diameter greater than about 1 micron.This critical fraction of material was believed to bridge pores in thewood, and, once the pores were bridged, substantially all the remainingparticles, including those having a diameter less than 0.2 microns,subsequently plated on the wood surface.

Further, extended grinding times using milling media routinely used inthe art 1) will not provide a more uniform product, and 2) will notsignificantly lower the d₅₀. It is known that compounds can be reducedto a particular particle size distribution, where further milling withthat media has virtually no effect. For example, we wet milled a ChampDP® material described above (having a d₅₀ of 0.2 microns, but a d₉₅over a micron) for two days using 2 mm zirconia beads as the media, andthe injectability and d₅₀ of the resultant composition was essentiallyunchanged. Along those lines, U.S. Published Patent Application No.2004/0050298 A1, in the unrelated art of formulating pigments, disclosesthat wet milling in a pearl mill with mixed zirconium oxide balls havinga diameter of from 0.1 to 0.3 mm could provide a desired product in 20to 200 minutes, but that longer milling periods had no significanteffect on the properties of the product, and that “as a result, the riskof overmilling can be excluded, with very great advantage for themeeting of specifications, especially if it is ensured that the radialspeed of the mill is not too high.”

U.S. Published Patent Application No. 2002/0047058 A1, which relates topreparing certain pharmaceutical formulations, discusses milling thepharmaceuticals with 0.5 mm diameter zirconium (sp) medical to obtainpharmaceutical formulations having particle diameters less than 0.5microns. In addition, U.S. Published Patent Application No. 2004/0051084A1 described manufacturing polymer particles comprising recurringthiophene units and polystyrenesulfonic acid by oxidative polymerizationof ethylenedioxythiophene in the presence of polystyrenesulfonic acidand subsequent milling with 0.5 mm diameter zirconia. Further, U.S.Published Patent Application No. 2002/0055046 A1 describes millingtitanium diozide with zirconia beads which have a diameter of 0.5 mm(manufactured by Nikkato Co., Ltd), where the resultant mean particlediameter of the titanium dioxide was 2.5 microns. Also, severalpublished applications relate to milling photographic compositions witha 0.5 mm zirconia media.

While it is known to grind certain materials to smaller size, certainbiocides are particularly resistant to grinding to less than 1 microndiameter. What is needed in the art is a process whereby a wide varietyof biocides can be readily milled to a particle size distribution whered₅₀ is less than 1 micron, preferably less than 0.7 microns.

The lowest d₅₀ obtainable from grinding with a particular media willdepend on the properties of material being ground. Several biocides canpurportedly be milled to a d₅₀ below about 1 micron, and occasionallybelow 0.5 micron. These biocides therefore have physical properties thatdiffer from those of chlorothalonil, making them easier to grind thanchlorothalonil. For example, it has been reported that millingtriphenyltin acetate,1-methyl-3-(2-fluoro-6-chlorophenyl)-5-(3-methyl-4-bromothien-2-yl)-1H-1,2,4-triazole,Spinosad insecticide, epoxiconazole, chlorpyrifos, and certain othermaterials to sub-micron size using milling materials that are outsidethe scope of this invention (see, e.g., U.S. Published PatentApplication No. 2001/0051175 A1). However, we believe that using themethod of this invention will provide a narrower particle sizedistribution than the prior art milling methods.

What is needed in the art is a process whereby a wide variety ofbiocides can be readily milled to a particle size distribution where d₉₀is less than 1 micron, preferably less than 0.7 microns.

Mentioning a reference in this background section is explicitly not aconcession that such reference constitutes prior art under the patentlaws of any country in which this application is pending. We found noreference in the published applications which relates to milling asparingly soluble inorganic biocidal compound, for example copperhydroxide, with 0.5 mm zirconia. We found no reference in the publishedapplications which relates to milling an organic fungicide with 0.5 mmzirconia media. We, in particular, found no reference in the publishedapplications which related to milling chlorothalonil with 0.5 mmzirconia media.

It would be an advantage in the art to provide a pesticide formulationof fairly uniformly sized submicron organic pesticide particles. Itwould be an advantage in the art to provide a method to routinely andpredictably: 1) prepare a pesticide formulation of fairly uniformlysized submicron organic pesticide particles; 2) a pesticide formulationof fairly uniformly sized submicron organic pesticide particles withsub-micron sparingly soluble inorganic biocidal particles; and 3) amethod of manufacturing the aforesaid formulations that will allow theformulation to have commercial application in the fields of a) foliarapplications, b) wood preservative treatments, c) turf applications, andd) non-fouling paints and coatings.

SUMMARY OF THE INVENTION

One of the key aspects of the present invention is not just attainingsmaller particles but also rendering the particles fairly uniform. Anygrinding of a partially crystalline material will produce some smallfraction of sub-micron particles.

A principal aspect of this invention is providing a method of producinga metaldehyde product where the d₅₀ is below 1 micron, preferably below0.7 microns, and for certain applications, below 0.4 microns, forexample between about 0.1 microns and about 0.3 microns. Anotherprincipal aspect of this invention is providing a method of producing azineb product where the d₅₀ is below 1 micron, preferably below 0.7microns, and for certain applications, below 0.4 microns, for examplebetween about 0.1 microns and about 0.3 microns. Another principalaspect of this invention is providing a method of producing a Ziramproduct where the d₅₀ is below 1 micron, preferably below 0.7 microns,and for certain applications, below 0.4 microns, for example betweenabout 0.1 microns and about 0.3 microns. Another principal aspect ofthis invention is providing a method of producing a Ferbam product wherethe d₅₀ is below 1 micron, preferably below 0.7 microns, and for certainapplications, below 0.4 microns, for example between about 0.1 micronsand about 0.3 microns. Another principal aspect of this invention isproviding a method of producing a maneb product, a Mancozeb product, anda Maneb/Mancozeb product where the d₅₀ is below 1 micron, preferablybelow 0.7 microns, and for certain applications, below 0.4 microns, forexample between about 0.1 microns and about 0.3 microns. Anotherprincipal aspect of this invention is providing a method of producing aTPTH product where the d₅₀ is below 1 micron, preferably below 0.7microns, and for certain applications, below 0.4 microns, for examplebetween about 0.1 microns and about 0.3 microns.

For foliar applications, another principal aspect of this invention isproviding a method of producing a each of the above products where thed₉₀ is less than about 4 times the d₅₀, preferably less than three timesthe d₅₀; where the d₁₀ is advantageously greater than about ¼th the d₅₀,preferably greater than about ⅓rd the d₅₀.

For wood preservation applications, another principal aspect of thisinvention is providing a method of producing a each of the aboveproducts where the d₉₈, preferably the d₉₉, is less than about 4 timesthe d₅₀, preferably less three times the d₅₀.

A first aspect of the invention is a method of preparing a organicbiocide product having a d₅₀ equal to or less than about 1 micron,comprising the steps of: 1) providing the solid organic biocide, and aliquid comprising a surface active agent, to a mill; providing a millingmedia comprising an effective amount of milling beads having a diameterbetween 0.1 mm and 0.8 mm, preferably between about 0.2 mm and about 0.7mm, more preferably between about 0.3 mm and about 0.6 mm, wherein thesemilling beads have a density greater than about 3 grams/cm3, preferablyequal to or greater than 3.5 grams/cm3, more preferably equal to orgreater than 3.8 grams/cm3, most preferably equal to or greater than 5.5grams/cm3, for example a zirconia bead having a density of about 6grams/cm3; and 2) wet milling the material at high speed, for examplebetween 300 and 6000 rpm, more preferably between 1000 and 4000 rpm, forexample between about 2000 and 3600 rpm, where milling speed is providedfor a laboratory scale ball mill, for a time sufficient to obtain aproduct having a mean volume particle diameter of about 1 micron orsmaller, for example between about 5 minutes and 300 minutes, preferablyfrom about 10 minutes to about 240 minutes, and most preferably fromabout 15 minutes to about 60 minutes. As little as 5% by volume of themilling media need be within the preferred specifications for millingsome materials, but better results are obtained if greater than 10% byweight, preferably greater than 25% by weight, for example between 40%and 100% by weight of the milling material is within the preferredspecifications. For milling material outside the preferredspecifications, advantageously this material has a density greater than3 grams/cm³ and a diameter less than 4 mm, for example 1 or 2 mmzirconia or zirconium silicate milling beads.

A second aspect of the invention is a method of preparing a solidorganic biocide product comprising the steps of: 1) providing the solidorganic biocide to a mill, and 2) milling the material with a millingmedia, wherein at least 25% by weight of the milling media has a densitygreater than 3.8 and a diameter between 0.1 and 0.7 mm.

A third aspect of the invention is a method of preparing a submicronorganic biocide product comprising the steps of: 1) providing the solidorganic biocide and a liquid to a mill, and 2) milling the material witha milling media comprising a zirconium oxide having a diameter betweenabout 0.1 mm and about 0.7 mm. The zirconium oxide can comprise anystabilizers and/or dopants known in the art, including, for example,cerium, yttrium, and magnesium.

A fourth aspect of the invention is a method of preparing a submicronorganic biocide product comprising the steps of: 1) providing the solidorganic biocide and a liquid to a mill, and 2) milling the material witha milling media comprising a zirconium silicate having a diameterbetween about 0.1 mm and about 0.7 mm and a density greater than about5.5 grams per cubic centimeter.

A fifth aspect of the invention is a method of preparing a submicronorganic biocide product for use as an injectable particulate woodpreservative, comprising the steps of: 1) providing the organic biocideto a mill, and 2) milling the material with a milling media having adensity greater than about 3.5 and having a diameter between about 0.1mm and about 0.7 mm. The invention also encompasses injecting thecomposition, which may be admixed with one or more injectableparticulate sparingly soluble biocidal salts.

Another key aspect of the invention is to make a variety of biocidalparticulate slurries available that are injectable into wood, therebyserving as a particulate wood preservative. Requirements ofinjectability into wood for substantially round, e.g., the diameter isone direction is within a factor of two of the diameter measured in adifferent direction, such as would be found in milled particles, are:

1) the d₉₆ is equal to or less than about 1 micron, but is preferablyabout 0.7 microns or less, more preferably about 0.5 microns or less,for example equal to or less than about 0.3 microns, or equal to or lessthan about 0.2 microns;

2) the d₉₉ is equal to or less than about 2 microns, preferably equal toor less than 1.5 microns, more preferably equal to or less than about 1micron; and

3), the d₅₀ is less than 0.5 microns, preferably less than 0.4 microns,and the d₅₀ is greater than 0.02 microns, more preferably greater than0.05 microns, for example a slurry where the d₅₀ is between about 0.1microns and about 0.3 microns. We believe the first criteria primarilyaddresses the phenomena of bridging and subsequent plugging of porethroats, the second criteria addresses the phenomena of forming a filtercake, and the third criteria addresses the issue of having particulatesdisposed in the wood which have an optimum size to ensure the treatmenthas an acceptable bio-activity and lifetime. Once a pore throat ispartially plugged, complete plugging and undesired buildup generallyquickly ensues.

A sixth aspect of the invention is a method of preparing a submicronorganic biocide product for use as a foliar treatment, or as an additivein paints or coatings, comprising the steps of: 1) providing the organicbiocide to a mill, and 2) milling the material with a milling mediahaving a density greater than about 3.5 and having a diameter betweenabout 0.1 mm and about 0.7 mm. The density of the milling media, andespecially of the milling media within the size range 0.3 to 0.7 mm, isadvantageously greater than about 3.8, for example greater than about 4,preferably greater than about 5.5, for example equal to or greater thanabout 6 grams per cubic centimeter. Ceramic milling media is preferredover metallic milling media.

The invention also encompasses a milled organic biocide product from anyof the above aspects and having a d₅₀ below about 1 micron, preferablybelow about 0.5 microns, and in many cases below about 0.3 microns, andwhich further may advantageously have a d₉₀ that is less than aboutthree times the d₅₀, preferably less than about two times the d₅₀. Theinvention also encompasses a organic biocide product from any of theabove aspects and having a d₅₀ below about 1 micron, preferably belowabout 0.5 microns, for example below about 0.3 microns, which furtherhas a d₉₅ that is less than about 1.4 microns, preferably less thanabout 1 micron, for example less than about 0.7 microns. In eachembodiment, the milling load is preferably about 50% of the volume ofthe mill, though loadings between 40% and 80% are efficient. In eachembodiment, advantageously water and surface active agents are added tothe product before or during milling. In each embodiment, the productcan be transported as a stable slurry, as a wettable powder, or asgranules that disintegrate on mixing with water to release the product.

In each embodiment, the milled particulate organic biocide may becombined with another milled inorganic particulate biocide, which may bea sparingly soluble biocidal salt such as copper hydroxide, zinchydroxide, and/or basic copper carbonate, which may be a substantiallyinsoluble biocidal oxide, such as Copper(I) oxide and/or zinc oxide, orany combinations thereof, wherein the other particulate biocideadvantageously also has a d₅₀ below about 1 micron, advantageously belowabout 0.5 microns. Alternatively, the second biocide may be aorganometallic compound, or another organic biocide.

When combining a plurality of particulate biocides into a slurry, it isadvantageous to make the dispersants and surfactants be compatible onewith another. Using anion dispersants on a first biocide and cationicdispersants on the second biocide can result in undesired interactionswhen the slurry is prepared.

The literature is full of inventions where two or more biocides have asynergistic effect. Often, this is the result of the second biocideprotecting the first biocide against organisms that can degrade thefirst biocide. For sparingly soluble or substantially insolublebiocides, such synergy can only be achieved if both biocides are in thearea to be protected. As a result, assuming relatively equal amounts ofbiocide, the two sparingly soluble or insoluble biocides should berelatively comparable in size to achieve the distribution needed foreffective synergy.

In some instances the second biocide is present in or as an organicliquid. In such cases, the organic liquid can be solubilized in solvent,emulsified in water, and then added to the first biocide before orduring milling, or less preferably after milling. The surface of thefirst biocide can be made compatible with the organic phase of theemulsion, and the liquid or solvated biocide can coat the primaryparticles. Advantageously, solvent can be withdrawn, for example byventing the gases above the biocidal composition or by drawing a vacuum.The liquid biocide will subsequently be bound to the surface of theparticulate biocide. Not only does this have the advantage of providingthe two biocides in close contact so synergy will be observed, but alsothis provides a method for broadcasting the liquid emulsion withoutexposing field personnel (if the composition is for foliarapplications), painters (if the composition is for non-fouling paints orcoatings), and wood preservation personnel from exposure to potentiallyharmful solvents. Advantageously, the particulate biocidal composition,be it slurry, wettable powder, or granules, can be substantially free ofvolatile solvents.

The present invention also encompasses methods of using the products ofthe above described processes, which include: injecting the particulateproduct of any of the processes described herein into wood if thecomposition is a wood preservative; spreading the particulate product ofany of the processes described herein over crops, if the composition isused as a foliar biocide; or mixing the particulate product of any ofthe processes described herein into a paint or coating formulation toimpart biocidal properties to the paint or coating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts sliced interior sections of a wood block wherein onesection is untreated, another section has been injected with copperoxide particulates at 0.22 lb/ft³, and a third section has been treatedwith injected copper hydroxide particulates and developed withdithiooxamide.

FIG. 2 depicts leaching data from wood measured following the AWPAStandard Method E11-97 for several various particulate slurries and twocontrols.

FIG. 3 depicts the clean appearance of a photograph of wood blocksinjected with copper hydroxide milled according to the process of thepresent invention as described in Example 3, compared with a photographof wood blocks injected (and plugged) with the un-milled (d50 of 2.5microns) copper hydroxide.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Unless otherwise specified, all compositions are given in percent, wherethe percent is the percent by weight based on the total weight of theentire component, e.g., of the particle, or to the injectablecomposition. In the event a composition is defined in “parts” of variouscomponents, this is parts by weight, such that the total number of partsin the composition is between 90 and 110.

As used herein, the terms “biocide” and “pesticide” are usedinterchangeably to mean a chemical agent capable of destroying livingorganisms, both microscopic and macroscopic, and not merely “pests.”

As used herein, the term “sparingly soluble” as it applies to inorganicsalts is meant to include salts with a K_(sp) in pure water of betweenabout 10⁻¹² to about 10⁻²⁴ for salts with only one anion, and from about10⁻¹⁴ to about 10⁻²⁷ for salts with two anions. Preferred inorganicbiocidal salts include copper salts, zinc salts, and tin salts, orcombinations thereof. In other embodiments, inorganic biocidal salts caninclude silver salts. The most preferred inorganic biocidal salts arecopper salts. Preferred sparingly soluble copper salts include copperhydroxide, basic copper carbonate, basic copper chloride (copperoxychloride), and basic copper sulfate. The most preferred inorganiccopper salts are copper hydroxide and basis copper carbonate.

One aspect of this invention is a method of making small particles oforganic biocide. Although U.S. Published Patent Application No.2001/0051175 A1 teaches that the nature of the material is not believedto be critical, it has surprisingly been discovered that grinding mediacontaining zirconium atoms are particularly preferable in millingmethods according to the invention. In addition, while not wishing to bebound by theory, it is hypothesized that using grinding media having asub-millimeter average particle size is necessary to achieve the desiredsub-micron particle size for many difficult-to-grind biocides, e.g.,chlorothalonil. The particles can be milled/ground at any suitableprocessing temperature where the agricultural product is stable.Typically, processing temperatures are not greater than the boilingpoint of water and not greater than the melting point of the solid, butambient temperature or only slight heating or cooling is preferred. Inseveral preferred embodiments, particularly those where the organicbiocide is chlorothalonil, the volume mean particle diameter is lessthan about 1 micron, more preferably less than about 400 nm, and mostpreferably less than about 300 nm.

Particle size as used herein is the mean weight average particlediameter, which is equivalent to the mean volume average particlediameter, also known as d₅₀. For larger particles this “average” valuecan be determined from settling velocity in a fluid, which is apreferred method of measuring particle size. Unless otherwise specified,as used herein the biocide particle diameter is given as the d₅₀ meanvolume average diameter. The d_(xx) is the diameter where the subscript“xx” is the percent of the volume of the solid material that has anaverage diameter smaller than the stated diameter. Other key parameters,such as d₈₀, d₉₅, and d₉₉, are similarly defined and are useful forvarious applications where not only is the mean volume particle diameterimportant but also the amount of larger particles (the sizedistribution, especially in the higher particle diameter range).Particle diameter can be beneficially determined by Stokes Law settlingvelocities of particles in a fluid, for example with a Model LA 700 or aCAPA™ 700 sold by Horiba and Co. Ltd., or a Sedigraph™ 5100Tmanufactured by Micromeritics, Inc., which uses x-ray detection andbases calculations of size on Stoke's Law, to a size down to about 0.2microns. Smaller sizes are beneficially determined by for example adynamic light scattering method, preferably with a Coulter™ counter, orwith a laser scattering method, or electron microscopy.

The preferred organic biocides for use with this invention include thoseorganic biocides that are substantially insoluble, or are only sparinglysoluble, in water, and also which are substantially stable againstweathering. The reason is that the smaller particles of this inventionmust be sufficiently bioactive and must last a commercially acceptabletime. For sparingly soluble organic biocides, enhanced bioactivity maybe obtained due to the greater allowable coverage (number of particles)and tenacity associated with smaller particles, as opposed to largerparticles of the same organic biocide. Enhanced bioactivity is asignificant factor, as it allows the use of less biocide in anapplication.

By substantially insoluble (or sparingly soluble, as the term relates toorganic biocides), we mean the organic biocide has a solubility in waterof less than about 0.1%, and most preferably less than about 0.01%, forexample in an amount of between about 0.005 ppm and about 1000 ppm,alternatively between about 0.1 ppm and about 100 ppm or between about0.01 ppm and about 200 ppm. It should be understood that the solubilityin water of many pesticides are pH-dependent, as a result of thefunctional groups they contain. Thus, biocides with carboxylic acidgroups or with sulfonamide or sulfonylurea groups, for example, may meetthe low solubility requirements at low pH but may be too highly solubleat higher pH values. The pH of the aqueous dispersion can be adjusted toensure substantial insolubility, or at least sparing solubility, ofthese biocides.

The organic biocide beneficially has a half life in water from about pH3 to about pH 11 of at least about 2 days, preferably at least about oneweek. The organic biocide beneficially is resistant to photolysis bysunlight. By “resistant to photolysis,” we mean that particles having anaverage diameter of about 0.3 to about 0.5 microns will maintain atleast 50% of their activity, measured against the target organism, afterexposure to about 12 hours per day of sunlight at about 75% humidity andambient temperature for 14 days. Finally, the organic biocide should besubstantially non-volatile at ambient conditions, by which we mean thatweight of the particles used in the above described test for photolysisshould, at the end of the test, be within about 20% of the weight of theparticles before the test began.

While it is not related to the performance of the particulate product,the preferred organic biocides are crystalline or semi-crystalline andhave a melting temperature in excess of 100° C. Such properties tend tosimplify the milling process.

Generally, the processes of this invention produce slurries orsuspensions of particulate biocidal material where the particle sizedistribution, in various embodiments, has the following characteristics:A) a volume mean diameter, d₅₀, of less than about 1 micron and a d₉₀ ofless than about 2 microns; B) a volume mean diameter, d₅₀, of less thanabout 0.6 micron and a d₉₀ of less than about 1.4 microns, preferablyless than about 1 micron; C) a volume mean diameter, d₅₀, of less thanabout 0.4 micron and a d₉₀ of less than about 1 micron, preferably lessthan about 0.7 microns; and or D) a volume mean diameter, d₅₀, betweenabout 0.1 and 0.3 microns and d₉₀ that is less than about 3 times thed₅₀. The preferred processes can provide a tighter control on particlesize, e.g., a particulate organic biocide composition having a d₅₀ lessthan about 1 micron, preferably less than about 0.5 microns, having ad₉₀ less than about twice the d₅₀, and optionally having a d₁₀ greaterthan about one half the d₅₀. Even more preferably, the preferredprocesses can provide a particulate organic biocide composition having ad₅₀ less than 1 micron, preferably less than 0.5 microns, having a d₉₅less than about twice the d₅₀, and optionally having a d₅ greater thanabout one half the d₅₀.

Such tight particle size distributions is beneficial in all applicationsand can be as important as, if not more important than, the meanparticle size. The examples in U.S. Published Patent Application No.2004/0063847 A1 shows why this is so. For sparingly soluble andessentially insoluble biocides, protection depends on having a particleof the biocide within a particular area or volume of the substrate to beprotected. The longevity of any particle, the rainfastness of anyparticle, and the suspendability of any particle are all functions ofthe particle diameter.

The U.S. Published Patent Application No. 2004/0063847 describe achlorothalonil suspension having a distribution such that 90% of theparticles have a diameter less than 0.5 microns and having a d₅₀ of“less than 3 microns” (meaning between 2 and 3 microns). Hypothetically,this chlorothalonil suspension can have 95 particles with 0.4 micronsparticle diameter for every 5 particles with 2.4 microns particlediameter. The mass of each of the larger particles is larger than themass of all 95 of the smaller particles combined, and the 5 largerparticles constitute about 91% of the total biocide in the formulation.The bigger particles do not protect a significantly larger area of forexample a leaf than does the smaller particles. In such a scenario, if aleaf requires 100 biocide particles, it will, on average, get 95 smallparticles and 5 large particles of biocide. The amount of biocide, forexample in pounds per acre, needed to obtain the 100 particles is over12 times the amount if all 100 particles were smaller particles. Also,such a composition could not be injected into wood, as the largeparticles would plug the surface of the wood and make unsightly stains,and the homogeneity of the penetration would be compromised. Inaddition, such a composition would make an unsightly coating of paint,as the large particles of biocide would disrupt the thinner coating ofpigment. Further, for foliar applications, the larger particles are muchmore susceptible to being washed from the surface than are smallerparticles, so in a short time as much as 91% of the biocide mass may bewashed away.

If, on the other hand, the d₉₀ is within a factor of two of the d₅₀ andthe d₅₀ is, for example, 0.4 microns, then the situation changesradically. Such a composition may be simplified to a composition having95 particles of 0.4 microns diameter, and about two particles withdiameter of 0.8 microns. In this case, the larger particles will haverainfastness closer to the smaller particles, the larger particles wouldbe injectable into wood, and less than 10-20% of the mass of the biocidewill be in the larger particles. For these many reasons, having a narrowparticle size distribution is desirable.

While generally not necessary, the particle size distribution of theproduct of this invention can be further narrowed, for example, bysedimentation or by filtering or centrifuging the suspension at a speedsuch that substantially all particles less than a certain size areremoved. While a fraction of the particles may be lost to the recyclingprocess by such a refinement, this may be preferable if the desiredparticle size distribution can not otherwise be achieved.

Many biocides can not be reduced to particle size d₅₀ less than about 1micron and d₉₀ less than about 2 times d₅₀ when grinding withconventional media, e.g., 1 mm zirconia, 2 mm steel balls, and the like,at commercially acceptable milling speeds. These biocides willparticularly benefit from the process of this invention, as the materialand procedures described here will allow commercial production and useof products having biocide particulates with a size distribution d₅₀less than about 0.7 microns and d₉₀ less than about 2 times d₅₀. Suchbiocides are known generally in the art.

Biocides include herbicides, insecticides, and fungicides, and,particularly important where woods are the substrate, moldicides.Examples of classes of compounds that have insecticidal activity andmeet the solubility (and optionally also the crystallinity and meltingpoint) requirements include, but are not restricted to, benzoyl ureassuch as hexaflumuron, diacylhydrazines such as tebufenozide, carbamatessuch as carbofuran, pyrethroids such as alpha-cypermethrin,organophosphates such as phosmet, triazoles, and natural products suchas spinosyns.

Examples of classes of compounds that have herbicidal activity and meetthe solubility (and optionally also the crystallinity and melting point)requirements include, but are not restricted to, imidazolinones such asimazaquin, sulfonylureas such as chlorimuron-ethyl, triazolopyrimidinesulfonamides such as flumetsulam, aryloxyphenoxy propionates such asquizalofop ethyl, aryl ureas such as isoproturon and chlorotoluron,triazines such as atrazine and simazine, aryl carboxylic acids such aspicloram, aryloxy alkanoic acids such as MCPA, chloroacetanilides suchas metazachlor, dintroanilines such as oryzalin, pyrazoles such aspyrazolynate, and diphenyl ethers such as bifenox.

Examples of classes of compounds that have fungicidal activity and meetthe solubility (and optionally also the crystallinity and melting point)requirements include, but are not restricted to, morpholines such asdimethomorph, phenylamides such as benalaxyl, azoles such ashexaconazole, strobilurins such as azoxystrobin, phthalonitriles such aschlorothalonil, and phenoxyquinolines such as quinoxyfen. A preferredclass of materials for use in this process include the class of biocidalphthalimides, of which chlorothalonil is a prime example.

Additionally or alternately, other acceptable biocides can include, butare not limited to, diuron, chlorotoluron, simazine, atrazine,carbendazime, maneb, mancozeb, fentin hydroxide, endosulfan, andcombinations thereof.

Additionally or alternately, other acceptable biocides can include, butare not limited to, amitraz, azinphos-ethyl, azinphos-methyl,benzoximate, fenobucarb, gamma-HCH, methidathion, deltamethrin, dicofol,dioxabenzafos, dioxacarb, dinobuton, endosulfan, bifenthrin, binapacryl,bioresmethrin, chlorpyrifos, chlorpyrifos-methyl, EPNethiofencarb,cyanophos, cyfluthrin, tetradifon, cypermethrin, tralomethrin,bromophos, N-2,3-dihydro-3-methyl-1,3-thiazol-2-ylidene-xylidene,2,4-parathion methyl, bromopropylate, butacarboxim, butoxycarboxin,chlordimeform, phosalone, chlorobenzilate, phosfolan, chloropropylate,phosmet, chlorophoxim, promecarb, fenamiphos, quinalphos, resmethrin,temephos, pirimiphos-ethyl, tetramethrin, pirimiphos-methyl, xylylcarb,profenofos, acrinathrin, propaphos, allethrin, propargite, benfuracarb,propetamphos, bioallethrin, pyrachlofos, bioallethrin S, tefluthrin,bioresmethrin, terbufos, buprofezin, tetrachlorinphos, chlorfenvinphos,tralomethrin, chlorflurazuron, triazophos, chlormephos, pyrachlofos,tefluthrin, terbufos, tetrachlorinphos, cycloprothrin, betacyfluthrin,cyhalothrin, cambda-cyhalothrin, tralomethrin, alpha-cypermethrin,triazophos, beta-cypermethrin, cyphenothrin, demeton-S-methyl,dichlorvos, disulfoton, edifenphos, empenthrin, esfenvalerate,ethoprophos, etofenprox, etrimphos, fenazaquin, fenitrothion,fenthiocarb, fenpropathrin, fenthion, fenvalerate, flucythrinate,flufenoxuron, tau-fluvalinate, formothion, hexaflumuron, hydroprene,isofenphos, isoprocarb, isoxathion, malathion, mephospholan, methoprene,methoxychlor, mevinphos, permethrin, phenothrin, phenthoate, benalaxyl,biteranol, bupirimate, cyproconazole, carboxin, tetraconazole,dodemorph, difenoconazole, dodine, dimethomoph, fenarimol, diniconazole,ditalimfos, ethoxyquin, myclobutanil, etridiazole, nuarimol,fenpropidin, oxycarboxin, fluchloralin, penconazole, flusilazole,prochloraz, imibenconazole, tolclofos-methyl, myclobutanil, triadimefon,propiconazole, triadimenol, pyrifenox, azaconazole, tebuconazole,epoxyconazole, tridemorph, fenpropimorph, triflumizole, 2,4-D esters,diclofop-methyldiethatyl, 2,4-DB esters, dimethachlor, acetochlor,dinitramine, aclonifen, ethalfluralin, alachlor, ethofumesate,anilophos, fenobucarb, benfluralin, fenoxapropethyl, benfuresate,fluazifop, bensulide, fluazifop-P, benzoylprop-ethyl, fluchloralin,bifenox, flufenoxim, bromoxynil esters, flumetralin, bromoxynil,flumetralin, butachlor, fluorodifen, butamifos, fluoroglycofen ethyl,butralin, fluoroxypyr esters, butylate, carbetamide, chlomitrofen,chlorpropham, cinmethylin, clethodim, clomazone, clopyralid esters, CMPPesters, cycloate, cycloxydim, desmedipham, dichlorprop esters, flurecolbutyl, fluorochloralin, haloxyfop, ethoxyethyl, haloxyfop-methyl,ioxynil esters, isopropalin, MCPA esters, mecoprop-P esters,metolachlor, monalide, napropamide, nitrofen, oxadiazon, oxyfluorfen,pendimethalin, phenisopham, phenmedipham, picloram esters, pretilachlor,profluralin, propachlor, propanil, propaquizafop, pyridate,quizalofop-P, triclopyr esters, tridiphane, trifluralin, and the like,and any combination thereof.

Chlorothalonil—The most preferred organic biocide is chlorothalonil,CAS# 1897-45-6, also known as 2,4,5,6-tetrachloro-1,3-dicyanobenzene,chlorothananil, Tetrachloroisophthalonitrile (TCIPN), and2,4,5,6-tetrachloro-1,3-Benzenedicarbonitrile. Technical chlorothalonilis an odorless, white, crystalline solid melting at about 250° C.Chlorothalonil is commercially available in particles having diametersgreater than about 2 microns. Chlorothalonil is variously used in woodpreservation to a limited extent, but is also used as a turf and cropfungicide, anti-fouling pigment and mildewcide in coatings. It issubstantially insoluble in water (solubility is 0.6-1.2 ppm and isslightly soluble in acetone and xylene. It has low volatility (9.2 mmHgat 170 C). In acid and neutral aqueous preparations, it is relativelystable but has a half life of about 38 days in water at a pH of about 9.It is thermally stable and is resistant to photolysis by ultravioletradiation. It is also nonvolatile under normal field conditions and isnot corrosive. Chlorothalonil is known to be difficult to grind andproducts are usually supplied as particulates having diameters in the2-4 micron range because of this.

The process of this invention is capable of producing a series oforganic biocide, e.g., chlorothalonil products with a procedure that issufficiently cost effective that the organic biocide, e.g.,chlorothalonil can be used for foliar agricultural treatments, woodpreservatives, and anti-fouling paints, inter alia. These applicationsare extremely cost sensitive, and the process of this invention can beperformed at a cost that is a small fraction of the cost of the rawbiocidal material. In various embodiments, the methods of this inventionare useful to produce a dispersion of non-agglomerating or interactingparticles comprising more than about 20% by weight, typically more thanabout 50% by weight, and often more than about 80% by weight, of organicbiocide, e.g., chlorothalonil, with the balance of the particles, ifany, typically comprising surface active agents such as stabilizers anddispersants, where the particle size distribution, in variousembodiments, can have the following characteristics: A) a volume meandiameter, d₅₀, of less than about 1 micron and a d₉₀ of less than about2 microns; B) a volume mean diameter, d₅₀, of less than about 0.6 micronand a d₉₀ of less than about 1.4 microns, preferably less than about 1micron; C) a volume mean diameter, d₅₀, of less than about 0.4 micronand a d₉₀ of less than about 1 micron, preferably less than about 0.7microns; and/or D) a volume mean diameter, d₅₀, between about 0.1 and0.3 microns and d₉₀ that is less than about 3 times the d₅₀.

Other organic biocides useful for the process of this invention arethose solid biocides listed in U.S. Pat. No. 5,360,783, the disclosureof which is incorporated by reference, includingo,o-dimethyl-o-4-methylthio-m-tolyl-phosphorothioate (Baycid),s-4-chlorobenzyldiethylthiocarbamate (Saturn),o-sec-butylphenylmethylcarbamate (BPMC),dimethyl-4,4-(o-phenylene)bis(3-thioallophanate) (Topsin-Methyl),4,5,6,7-tetrachlorophthalide (Rabcide),o,o-diethyl-o-(2,3-dihydro-3-oxo-2-phenylpyridazin-6-yl)-phosphorothioate(Ofunack) and manganese ethylenebis(dithiocarbamate) (Maneb), where theparticle size distribution, in various embodiments, can have thefollowing characteristics: A) a volume mean diameter, d₅₀, of less thanabout 1 micron and a d₉₀ of less than about 2 microns; B) a volume meandiameter, d₅₀, of less than about 0.6 micron and a d₉₀ of less thanabout 1.4 microns, preferably less than about 1 micron; C) a volume meandiameter, d₅₀, of less than about 0.4 micron and a d₉₀ of less thanabout 1 micron, preferably less than about 0.7 microns; and/or D) avolume mean diameter, d₅₀, between about 0.1 and 0.3 microns and d₉₀that is less than about 3 times the d₅₀. Maneb, for example, iscommercially available in particle sizes greater than about 1.4 microns.

In another embodiment, the process of the invention is also useful forpreparing a submicron metaldehyde composition. In another embodiment,the process of the invention is also useful for preparing a submicrontriphenyltin hydroxide composition. In another embodiment, the processof the invention is also useful for preparing a submicron Mancozebcomposition. In another embodiment, the process of the invention is alsouseful for preparing a submicron Zineb composition. In anotherembodiment, the process of the invention is also useful for preparing asubmicron Ziram composition. In another embodiment, the process of theinvention is also useful for preparing a submicron Ferbam composition.In each of these embodiments (and, in fact, with any of the biocidesreferenced herein), the particle size distribution of the biocide and/orthe composition can have the following characteristics: A) a volume meandiameter, d₅₀, of less than about 1 micron and a d₉₀ of less than about2 microns; B) a volume mean diameter, d₅₀, of less than about 0.6 micronand a d₉₀ of less than about 1.4 microns, preferably less than about 1micron; C) a volume mean diameter, d₅₀, of less than about 0.4 micronand a d₉₀ of less than about 1 micron, preferably less than about 0.7microns; and/or D) a volume mean diameter, d₅₀, between about 0.1 and0.3 microns and d₉₀ that is less than about 3 times the d₅₀.

Generally the processes of this invention produce slurries orsuspensions of particulate biocidal material. This material may be driedinto a wettable powder, often with the addition of surface active agentsand/or fillers, where fillers may include dissolvable buffering agents.The compositions resulting from the processes described herein mayalternatively be formulated into fast-dissolving/releasing granules ortablets comprising the submicron organic biocidal material, such thatthe biocide particles are quickly released to form stable suspensionswhen the granule contacts water. One example of a biocide composition ingranular or tablet form, which rapidly disintegrates and disperses inwater, includes, e.g., about 40 parts particulate biocide, about 10 toabout 40 parts salts, preferably carbonate and/or bicarbonate salts,about 1 to about 20 parts solid carboxylic acids, about 5 to about 50parts stabilizers and/or dispersants, and up to about 20 parts starchesand or sugars. Another exemplary dissolvable biocide granulecomprises: 1) about 50-75% of a first finely-divided (submicron),essentially water-insoluble biocide, such as is produced by theprocesses of this invention; 2) optionally about 7-15% of a secondparticulate biocide, which may be a biocidal inorganic salt; 3) about2-20% of a stabilizer and/or dispersing agent; 4) about 0.01-10% of awetting agent; 5) about 0-2% of an antifoaming agent; 6) about 0-10% ofa diluent; and optionally 7) about 0-2% of a chelating agent.

Conventional mills used for particulate size reduction in a continuousmode incorporate a means for retaining milling media in the milling zoneof the mill, i.e., the milling chamber, while allowing the dispersion orslurry to recirculate through the mill into a stirred holding vessel.Various techniques have been established for retaining media in thesemills, including rotating gap separators, screens, sieves,centrifugally-assisted screens, and similar devices to physicallyrestrict passage of media from the mill. The milling process can be adry process, e.g., a dry milling process, or a wet process, i.e.,wet-grinding. In one embodiment, this milling is performed in accordancewith the wet milling process of U.S. Pat. No. 5,145,684, using a liquiddispersion medium and a surface modifier described therein. Usefulliquid dispersion media include water, aqueous salt solutions, ethanol,butanol, hexane, glycols, and the like. Water, particularly water havingadded surface active agents, is a preferred medium.

The preferred milling procedure includes wet milling, which is typicallydone at mill setting between about 1000 rpm and about 4000 rpm, forexample between about 2000 rpm and about 3000 rpm. Faster revolutionsprovide shorter processing times to reach the minimum product particlesize. Generally, the selection of the milling speed, including the speedin a scaled up commercial milling machine, can be readily determined byone of ordinary skill in the art without undue experimentation, giventhe benefit of this disclosure.

In an alternate procedure, the biocide can be double-milled, e.g., asused to mill chitosan in paragraphs [0070]-[0074] of U.S. PublishedPatent Application No. 2004/0176477 A1, the disclosure of which isincorporated by reference herein. In one such embodiment, for example,the milling media in the first milling step can have a diameter of about0.5 to 1 mm, preferably 0.5 to 0.8 mm, while the milling media in thesecond milling step can have a diameter of about 0.1-0.4 mm, preferablyabout 0.3 mm.

The milling temperature of the organic biocide can be at least about 40°C. below, preferably at least about 100° C. below the glass transitiontemperature (or the softening temperature, if there is no glasstransition temperature, or the melting temperature, if the biocide isinorganic). Preferably, the milling takes place at a process temperatureof about ambient temperature to about 40° C. To maintain an ambientmilling temperature, generally active cooling is required, and the costof active cooling generally exceeds the benefit obtained.

The milling media, also called grinding media or milling beads, iscentral to this invention. The selection of milling media is expresslynot a routine optimization. The use of this media allows an averageparticle size and a narrow particle size distribution that hadpreviously not been obtainable in the art.

The milling media advantageously comprises or consists essentially of azirconium-based material. The preferred media is zirconia (density ˜6g/cm³), which includes preferred variants such as yttria stabilizedtetragonal zirconium oxide, magnesia stabilized zirconium oxide, andcerium doped zirconium oxide. For some biocides, zirconium silicate(density ˜3.8 g/cm³) is useful. However, for several biocides such aschlorothalanil, zirconium silicate will not achieve the required actionneeded to obtain the narrow sub-micron range of particle sizes inseveral preferred embodiments of this invention.

In an alternate embodiment, at least a portion of the milling mediacomprises or consists essentially of metallic material, e.g., steel. Themilling medium is a material having a density greater than about 3.5,preferably at least about 3.8, more preferably greater than about 5.5,for example at least about 6 g/cm³.

We believe that density and particle size are the two most importantparameters in the milling media. Preferably the milling media comprisesor consists essentially of particles, having a size (diameter) betweenabout 0.1 mm and about 0.8 mm, preferably between about 0.3 mm and about0.7 mm, for example between about 0.4 mm and 0.6 mm. Also preferably,the milling media can have a density greater than about 3.8 g/cm³,preferably greater than about 5.5 g/cm³, more preferably greater thanabout 6 g/cm³. The zirconium-based milling media useful in the presentinvention can comprise or consist essentially of particles having adiameter (as the term is used in the art) between about 0.1 mm and about0.8 mm, preferably between about 0.3 mm and about 0.7 mm, for examplebetween about 0.4 mm and 0.6 mm.

The media need not be of one composition or size. Further, not all themilling material need be the preferred material, i.e., having apreferred diameter between 0.1 mm and 0.8 mm, preferably between 0.2 mmand 0.7 mm, more preferably between 0.3 mm and 0.6 mm, and having apreferred density equal to or greater than 3.8 grams/cm³, preferablygreater than or equal to 5.5 grams/cm³, more preferably greater than orequal to 6 grams/cm³. In fact, as little as 10% of this media willprovide the effective grinding. The amount of the preferred millingmedia, based on the total weight of media in the mill, can be between 5%and 100%, is advantageously between 10% and 100%, and is preferablybetween 25% and 90%, for example between about 40% and 80%. Media notwithin the preferred category can be somewhat larger, say 1 mm to 4 mmin diameter, preferably from 1 mm to 2 mm in diameter, andadvantageously also has a density equal to or greater than 3.8grams/cm³. Preferably at least about 10%, preferably about 25%,alternately at least about 30%, for example between about 50% and about99%, of the media has a mean diameter of between about 0.1 mm to about0.8 mm, preferably between about 0.3 mm and about 0.6 mm, oralternatively between about 0.3 mm and about 0.5 mm. The remaining media(not within the specified particle size) can be larger or smaller, but,in preferred embodiments, the media not within the specified size islarger than the media in the specified size, for example at least aportion of the milling media not within the preferred size range(s) hasa diameter between about 1.5 and about 4 times, for example betweenabout 1.9 and about 3 times, the diameter of the preferred media. Apreferred media is 0.5 mm zirconia, or a mixture of 0.5 mm zirconia and1-2 mm zirconia, where at least about 25% by weight of the media is 0.5mm zirconia. The remaining media need not comprise zirconium, butadvantageously will have a density greater than 3.5 g/cc. Using mediacomprising a zirconia portion and a steel portion can be advantageous.

In an alternate embodiment, the metal, e.g., steel milling media usefulin the present invention can comprise or consist essentially ofparticles having a diameter (as the term is used in the art) betweenabout 0.1 mm and about 0.8 mm, preferably between about 0.3 mm and about0.7 mm, for example between about 0.4 mm and 0.6 mm. The media need notbe of one composition or size. Preferably at least about 10%, preferablyabout 25%, alternately at least about 30%, for example between about 50%and about 99%, of the media has a mean diameter of between about 0.1 mmto about 0.8 mm, preferably between about 0.3 mm and about 0.6 mm, oralternatively between about 0.3 mm and about 0.5 mm. The remaining media(not within the specified particle size) can be larger or smaller, but,in preferred embodiments, the media not within the specified size islarger than the media in the specified size, for example at least aportion of the milling media not within the preferred size range(s) hasa diameter between about 1.5 and about 4 times, for example betweenabout 1.9 and about 3 times, the diameter of the preferred media. Theremaining media need not comprise steel, but advantageously will have adensity greater than 3.5 g/cc.

Advantageously, the average diameter of the milling media is preferablyabout 0.4 mm to about 0.6 mm, and more preferably about 0.5 mm, and ispreferably zirconia. If other media or sizes are present, beneficiallyat least about 25%, preferably at least about 50%, by weight of themilling media has an average particulate diameter of about 0.4 mm toabout 0.6 mm, and more preferably about 0.5 mm. Such media will providethe desired submicron and narrow particle size distribution describedherein. Generally, the use of milling media below about 0.1 mm diameteris discouraged, unless it is present with the recited amount of media inthe preferred size range. Generally, the milling media within thespecified size ranges of about 0.1 mm to about 0.8 mm, for example formabout 0.1 mm to about 0.7 mm or from about 0.1 mm to 0.6 mm, oralternatively from about 0.3 mm to about 0.6 mm or from about 0.4 mm toabout 0.5 mm, comprises or consists essentially of azirconium-containing compound, preferably zirconia.

Advantageously, the milling media loading can be between about 40% andabout 80% of the mill volume.

Advantageously, the organic biocide can be milled for a time betweenabout 10 minutes and about 8 hours, preferably between about 10 minutesand about 240 minutes, for example between about 15 minutes and about150 minutes. Again, the upper limit in time is significantly lessimportant than the lower limit, as the change in particle sizedistribution per hour of milling becomes exceedingly small as themilling time increases.

Ostwald ripening can occur whenever a component of the disperse phase iscapable of being transported through the continuous phase from oneparticle to another. The usual mechanism for such transport is bydissolution of the transportable material in the continuous phase, whichcan occur even if the solubility of the material is low. Other transportmechanisms, however, are possible. For example, even materials having avery low water solubility indeed, which might not be expected to displayOstwald ripening, can do so, when certain surfactants are used in thepreparation and stabilization of the emulsion. Such a phenomenon isbelieved to be due to transport of the water insoluble materials throughthe aqueous phase by dissolution in surfactant micelles. Variouscompounds to alleviate this problem are described, for example, in U.S.Pat. No. 6,074,986, the disclosure of which is incorporated byreference. On the other hand, some particles can get smaller with time.

Aqueous dispersing agents for such dispersed solids are well known tothose skilled in the art and include, but are not limited to, nonionicsurfactants such as ethylene oxide/propylene oxide block copolymers,polyvinyl alcohol/polyvinyl acetate copolymers, polymeric nonionicsurfactants such as the acrylic graft copolymers; anionic surfactantssuch as polyacrylates, lignosulfonates, polystyrene sulfonates, maleicanhydride-methyl vinyl ether copolymers, naphthalene sulfonic acidformaldehyde condensates, phosphate ester surfactants such as atristyrenated phenol ethoxylate phosphate ester, maleicanhydride-diisobutylene copolymers, anionically modified polyvinylalcohol/polyvinylacetate copolymers, and ether sulfate surfactantsderived from the corresponding alkoxylated nonionic surfactants;cationic surfactants; zwitterionic surfactants; and the like.

The milling of the organic biocides is advantageously performed in thepresence of an aqueous medium containing surfactants and/or dispersants,such as those known in the art. Use of other media, including forexample polar organic solvents such as alcohols, generally does notoffer added advantage sufficient to outweigh the cost and associatedhazards of milling with solvents. Because it is now possible to achievea smaller particle size and a narrower particle size distribution usingthe present invention than was previously known in the art, the numberand amount of stabilizers and/or dispersants are less critical. As usedherein, the term “surface active agent” includes both singular andplural forms and encompasses generally both stabilizers and dispersants.The surface active agent may be anionic, cationic, zwitterionic, ornonionic, or a combination thereof. Generally, higher concentrations ofsurface active agents present during milling result in a smallerparticle size.

However, because we have surprisingly found a milling media andconditions where very small particles and a narrow particle sizedistribution are obtainable, we can use less/lower amounts ofstabilizers and/or dispersants than would otherwise be used. Forexample, advantageously the total weight of surface active agents in thepresent invention can be less than about 1.5 times the weight of theparticulate organic biocide, preferably less than about the weight ofthe particulate organic biocide. A stabilizing amount of the surfaceactive agent can be used, generally not less than about 2%, andtypically not more than about 60% by weight, based on the weight of theparticulate organic biocide. Other adjuvants, such as: fillers includingbiocidal fillers such as zinc oxide and non-biocidal fillers such assilica; stabilizer/dispersants such as a poly (oxypropylene) blockcopolymer with poly (oxyethylene), commercially available from BASF,PROXEL GXL (1,2-benzisothiazolin-3-one, commercially available from ICI,and/or PVP K-30 poly(vinyl pyrrolidone), commercially available fromBAS; typical viscosity modifiers/stabilizers such as xanthan gumcommercially available from Kelco); typical anti-foaming agents such asAntifoam FG-10, a silicon emulsion commercially available from DowCorning; antifreeze such as propylene glycol; chelators such as EDTA,HEDP, and the like, can be added to the water before or during milling.Milling is best done in a wet mill or high speed media mill.

Examples of suitable classes of surface active agents include, but arenot limited to, anionics such as alkali metal fatty acid salts,including alkali metal oleates and stearates; alkali metal laurylsulfates; alkali metal salts of diisooctyl sulfosuccinate; alkyl arylsulfates or sulfonates, lignosulfonates, alkali metal alkylbenzenesulfonates such as dodecylbenzene sulfonate, alkali metal soaps,oil-soluble (e.g., calcium, ammonium, etc.) salts of alkyl aryl sulfonicacids, oil soluble salts of sulfated polyglycol ethers, salts of theethers of sulfosuccinic acid, and half esters thereof with nonionicsurfactants and appropriate salts of phosphated polyglycol ethers;cationics such as long chain alkyl quaternary ammonium surfactantsincluding cetyl trimethyl ammonium bromide, as well as fatty amines;nonionics such as ethoxylated derivatives of fatty alcohols, alkylphenols, polyalkylene glycol ethers and condensation products of alkylphenols, amines, fatty acids, fatty esters, mono-, di-, ortriglycerides, various block copolymeric surfactants derived fromalkylene oxides such as ethylene oxide/propylene oxide (e.g., PLURONIC™,which is a class of nonionic PEO-PPO co-polymer surfactant commerciallyavailable from BASF), aliphatic amines or fatty acids with ethyleneoxides and/or propylene oxides such as the ethoxylated alkyl phenols orethoxylated aryl or polyaryl phenols, carboxylic esters solubilized witha polyol or polyvinyl alcohol/polyvinyl acetate copolymers, polyvinylalcohol, polyvinyl pyrrolidinones (including those sold under thetradenames AGRIMER™ and GANEX™), cellulose derivatives such ashydroxymethyl cellulose (including those commercially available from DowChemical Company as METHOCEL™), and acrylic acid graft copolymers;zwitterionics; and the like; and mixtures, reaction products, and/orcopolymers thereof.

Additionally or alternatively, the surface active agent may include, butis not limited to, low molecular weight sodium lauryl sulfates, calciumdodecyl benzene sulfonates, tristyryl ethoxylated phosphoric acid orsalts, methyl vinyl ether-maleic acid half-ester (at least partiallyneutralized), beeswax, water soluble polyacrylates with at least 10%acrylic acids/salts, or the like, or a combination thereof.

Additionally or alternatively, the surface active agent may include, butis not limited to, alkyl grafted PVP copolymers commercially availableas GANEX™ and/or the AGRIMER™ AL or WP series, PVP-vinyl acetatecopolymers commercially available as the AGRIMER™ VA series, ligninsulfonate commercially available as REAX 85A (e.g., with a molecularweight of about 10,000), tristyryl phenyl ethoxylated phosphoricacid/salt commercially available as SOPROPHOR™ 3D33, GEROPON™ SS 075,calcium dodecylbenzene sulfonate commercially available as NINATE™ 401A, IGEPAL™ CO 630, other oligomeric/polymeric sulfonated surfactantssuch as Polyfon H (molecular weight ˜4300, sulfonation index ˜0.7, saltcontent ˜4%), Polyfon T (molecular weight ˜2900, sulfonation index ˜2.0,salt content ˜8.6%), Polyfon O (molecular weight ˜2400, sulfonationindex ˜1.2, salt content ˜5%), Polyfon F (molecular weight ˜2900,sulfonation index ˜3.3, salt content ˜12.7%), Reax 88B (molecular weight˜3100, sulfonation index ˜2.9, salt content ˜8.6%), Reax 100 M(molecular weight ˜2000, sulfonation index ˜3.4, salt content ˜6.5%),and Reax 825 E (molecular weight ˜3700, sulfonation index ˜3.4, saltcontent ˜5.4%), and the like.

Other notable surface active agents can include nonionic polyalkyleneglycol alkyd compounds prepared by reaction of polyalkylene glycolsand/or polyols with (poly)carboxylic acids or anhydrides; A-B-Ablock-type surfactants such as those produced from the esterification ofpoly(12-hydroxystearic acid) with polyalkylene glycols; high molecularweight esters of natural vegetable oils such as the alkyl esters ofoleic acid and polyesters of polyfunctional alcohols; a high molecularweight (MW>2000) salt of a naphthalene sulfonic acid formaldehydecondensate, such as GALORYL™ DT 120L available from Nufarm; MORWET EFW™available from Akzo Nobel; various Agrimer™ dispersants available fromInternational Specialties Inc.; and a nonionic PEO-PPO-PEO triblockco-polymer surfactant commercially available as PLURONIC™ from BASF.

Other examples of commercially available surface active agents includeAtlox 4991 and 4913 surfactants (Uniqema), Morwet D425 surfactant(Witco), Pluronic P105 surfactant (BASF), Iconol TDA-6 surfactant(BASF), Kraftsperse 25M surfactant (Westvaco), Nipol 2782 surfactant(Stepan), Soprophor FL surfactant (Rhone-Poulenc), Empicol LX 28surfactant (Albright & Wilson), Pluronic F108 (BASF).

In one embodiment, exemplary suitable stabilizing components includepolymers or oligomers having a molecular weight from about 250 to about10⁶, preferably from about 400 to about 10⁵, more preferably from about400 to about 10⁴, and can include, for example, homopolymers orco-polymers described in “Polymer Handbook,” 3rd Edition, edited by J.Brandrup and E. H. Immergut.

In another embodiment, exemplary suitable stabilizing components includepolyolefins such as polyallene, polybutadiene, polyisoprene,poly(substituted butadienes) such as poly(2-t-butyl-1,3-butadiene),poly(2-chlorobutadiene), poly(2-chloromethyl butadiene),polyphenylacetylene, polyethylene, chlorinated polyethylene,polypropylene, polybutene, polyisobutene, polybutylene oxides,copolymers of polybutylene oxides with propylene oxide or ethyleneoxide, polycyclopentylethylene, polycyclolhexylethylene, polyacrylatesincluding polyalkylacrylates and polyarylacrylates, polymethacrylatesincluding polyalkylmethacrylates and polyarylmethacrylates,polydisubstituted esters such as poly(di-n-butylitaconate),poly(amylfumarate), polyvinylethers such as poly(butoxyethylene) andpoly(benzyloxyethylene), poly(methyl isopropenyl ketone), polyvinylchloride, polyvinyl acetate, polyvinyl carboxylate esters such aspolyvinyl propionate, polyvinyl butyrate, polyvinyl caprylate, polyvinyllaurate, polyvinyl stearate, polyvinyl benzoate, polystyrene,poly-t-butyl styrene, poly (substituted styrene), poly(biphenylethylene), poly(1,3-cyclohexadiene), polycyclopentadiene,polyoxypropylene, polyoxytetramethylene, polycarbonates such aspoly(oxycarbonyloxyhexamethylene), polysiloxanes, in particular,polydimethyl cyclosiloxanes and organo-soluble substituted polydimethylsiloxanes such as alkyl, alkoxy, or ester substitutedpolydimethylsiloxanes, liquid polysulfides, natural rubber andhydrochlorinated rubber, ethyl-, butyl- and benzyl-celluloses, celluloseesters such as cellulose tributyrate, cellulose tricaprylate, andcellulose tristearate, natural resins such as colophony, copal, andshellac, and the like, and combinations or copolymers thereof.

In still another embodiment, exemplary suitable stabilizing componentsinclude co-polymers of styrene, alkyl styrenes, isoprene, butenes,butadiene, acrylonitrile, alkyl acrylates, alkyl methacrylates, vinylchloride, vinylidene chloride, vinyl esters of lower carboxylic acids,and α,β-ethylenically unsaturated carboxylic acids and esters thereof,including co-polymers containing three or more different monomer speciestherein, as well as combinations and copolymers thereof.

In yet another embodiment, exemplary suitable stabilizing componentsinclude polystyrenes, polybutenes, for example polyisobutenes,polybutadienes, polypropylene glycol, methyl oleate,polyalkyl(meth)acrylate e.g. polyisobutylacrylate orpolyoctadecylmethacrylate, polyvinylesters e.g. polyvinylstearate,polystyrene/ethyl hexylacrylate copolymer, and polyvinylchloride,polydimethyl cyclosiloxanes, organic soluble substituted polydimethylsiloxanes such as alkyl, alkoxy or ester substitutedpolydimethylsiloxanes, and plybutylene oxides or copolymers ofpolybutylene oxides with propylene and/or ethylene oxide.

In one embodiment, the surface active agent can be adsorbed onto thesurface of the biocide particle, e.g., in accordance with U.S. Pat. No.5,145,684.

Additionally, other additives may be included in the biocidalcompositions according to the invention for imparting particularadvantages or to elicit particular properties. These additives aregenerally known in the solution, emulsion, and/or slurry arts, and caninclude, e.g., anti-freeze agents such as glycols (for instance,ethylene and/or propylene glycol), inter alia.

The composition preferably comprises between about 0.05% and about 50%by weight of the particulate organic biocide, e.g., chlorothalonil, or amixture of two or more particulate biocides where one particulatebiocide is the organic particulate biocide and the other particulatebiocide is selected from other particulate organic biocides, particulateorganometallic biocides (e.g., Maneb), slightly soluble inorganicbiocides (e.g., copper hydroxide), or a combination thereof.

One of the advantages of the stable aqueous dispersion of the presentinvention is that it provides a means to prepare one-part formulationsof different biocides which are not only compatible with each other, butincompatible or unstable in each other's presence as well. For example,it may be desirable to combine a certain pesticide with a certainherbicide for a particular application but for the fact that the twobiocides (in solution, for example) react with each other faster thanthey can be applied to the desired site. However, in a stable aqueousdispersion of particulate biocides, these different and incompatiblebiocides can co-exist, at least temporarily, since they are shieldedfrom each other from reacting rapidly, so that an end user can mix theincompatible pesticides together and apply them to a site before theirefficacy is significantly diminished.

The particulate organic biocide is, in many embodiments, combined withone or more other organic biocides and/or particulate sparingly solublebiocidal inorganic salts. These inorganic biocidal salts can be milled,for example, using the same procedures and importantly the same millingmedia described for the organic pesticides. For instance, particulatecopper(I) oxide is useful and is readily milled by the processes of thisinvention.

Preferred inorganic copper salts include copper hydroxides; coppercarbonates; basic (or “alkaline”) copper carbonates; basic coppersulfates including particularly tribasic copper sulfate; basic coppernitrates; copper oxychlorides (basic copper chlorides); copper borates;basic copper borates; copper silicate; basic copper phosphate; andmixtures thereof. The particulate copper salts can have a substantialamount of one or more of magnesium, zinc, or both, e.g., between about 6and about 20 parts of magnesium per 100 parts of copper, for examplebetween about 9 and about 15 parts of magnesium per 100 parts of copper,wherein these cations are either dispersed within, or constitute aseparate phase within, a particulate. In preferred embodiments of theinvention, at least some particulates comprise copper hydroxide, basiccopper carbonate, or both.

Preferred inorganic zinc salts and compounds include the zinccomplements of the aforementioned copper salts, and expressly includeszinc oxide; the synergystic use of zinc oxide and chlorothalonil forpotatoes is described in U.S. Pat. No. 5,667,795, the disclosure ofwhich is incorporated herein by reference. This patent teaches that 2-4micron diameter chlorothalonil particles were useful with 1-4 microndiameter zinc oxide particles. However, we believe the claimed range inthis publication reflected what the inventors could manufacture. Incontrast, the preferred particle size range has a chlorothalonil d₅₀less than about 1.4 microns, for example not more than about 0.9 micronsor less than about 0.5 microns, alternately from about 0.1 microns toabout 0.35 microns, and preferably has a d₈₀ less than about 0.5microns, while the zinc oxide is useful with a d₅₀ less than about 1.5microns, for example less than about 1 micron, e.g., between about 0.3and about 0.7 microns. Other useful zinc salts include zinc hydroxide,zinc carbonate, zinc oxychloride, zinc fluoroborate, zinc borate, zincfluoride, and mixtures thereof.

In any of the above-described embodiments, the preservative can furthercomprise the substantially insoluble copper salt copper phosphate,Cu₃(PO₄)₂. However, basic copper phosphate is preferred for the solidparticulates, as it is more soluble and more bioactive than copperphosphate. Additionally, the phosphate ions can retard leaching ofcopper, neutralize acids in the wood, and in some instances help reducecorrosivity of the treated wood to metals.

Conversely but advantageously, basic copper borate has a lowersolubility than copper borate, which is advantageous because copperborate particles can dissolve fairly quickly, in terms of the expectedlife of a wood preservative. Basic copper borate has an advantage thatthe anion, borate, has advantageous biocidal and fire retardingproperties.

Mixtures of basic copper phosphate and basic copper sulfate are alsouseful, and they are often called basic copper phosphosulfate.

As copper salts are millable and injectable, and organic biocides thatare known to be difficult to mill are millable and injectable, there isno reason to doubt that organo-copper compounds will also not bemillable and injectable. In any of the embodiments, the preservative maycomprise copper organic materials, especially those materials having asparingly soluble partially crystalline nature, e.g., the ground copperorganic salts disclosed in U.S. Pat. No. 4,075,326. In any of theabove-described embodiments, the copper composition in copper-basedparticulates and/or copper-based particulate material can furthercomprise the substantially insoluble copper salt copper 8-quinolinolate.In any of the above-described embodiments, the composition can furthercomprise copper quinaldate, copper oxime, or both in particulate form.Its particularly noteworthy that organo-metallic meterials, such as thecopper salt of 8-hydroxyquinoline, copper oxime, and even traditionallyoil-borne biocides such as copper naphthaenate, can now be milled intosubmicon injectable particles, and injected into and dispersedthroughout wood, without use of dissolving oils. The zinc analogs areequally millable.

Additionally or alternately, selected finely ground crystalline ironoxides and hydroxides (excluding gel-like materials such as Goethite)can provide UV protective activity to wood and, like the copper and zincsalts described above, can be readily milled to form injectable slurriesusing processes of this invention, can be readily co-mingled with theparticulate organic biocide, and can be injected into the wood or usedin paint. Indeed, the media of this invention can mill certain ironoxides to a d50 below 0.1 microns. This iron salt can also be used as apigment, to help disguise the color of other components injected.Selected sparingly soluble nickel salts and finely ground nickel oxidecan provide biocidal activity to wood, and like the copper and zincsalts described above, can be readily milled to injectable slurriesusing processes of this invention, can be readily co-mingled with theparticulate organic biocide, and can be injected into wood or used inpaint. Selected sparingly soluble tin salts and finely ground tin oxidecan provide biocidal activity to wood and, like the copper and zincsalts described above, can be readily milled to injectable slurriesusing processes of this invention, can be readily co-mingled with theparticulate organic biocide, and can be injected into wood or used inpaint.

Selected copper salts of an unsaturated dibasic acid, such as fumaricacid, maleic acid, mesaconic acid, terephthalic acid, isophthalic acid,and the like, as well as other compounds described in U.S. Pat. No.4,075,326, can be formed into solids and milled according to theprocesses of the current invention. Other moieties, includingparticularly sulfonate moieties, can be substituted for one or both ofthe carboxylate moieties in the dibasic acids described above, and theresulting copper salt may again be sparingly soluble and thus millableand usable in the methods according to the invention. Further, coppersalts of organic acids having two carboxylate moieties separated by notone carbon atom but by two carbon atoms, e.g., copper succinate or thelike, can be ground and treated like other organic copper salts.

One or more liquid organic biocides can be coated onto the particulateorganic biocide, or onto the inorganic particulate biocide, ifavailable, or both. An emulsion having dispersed liquid biocides in asmall amount of solvent can be added to a composition containing theto-be-milled biocide before or during milling, for example, and thesolvent can be removed by evaporation or vacuum distillation to leavethe non-volatile liquid organic biocide, for example a triazole such astebuconazole, coated onto the particulates. In addition to combiningsynergistic combinations of biocides, this process could help moreevenly distribute the liquid biocide, which is often present in verysmall quantities.

Foliar Applications—Generally, the size of the particles for use infoliar applications will depend on the required duration of treatment aswell as on the weathering-resistance of each biocide. For biocides thatare substantially insoluble, like chlorothalonil, usually only theresistance to weathering is important. A small particle size coupledwith a narrow particle size distribution will allow a substantialreduction in the required dosage. This invention provides both a methodof manufacture and the product of this method, that is, a method ofproducing a chlorothalonil product where the d₅₀ is below 1 micron,preferably below 0.7 microns, and for certain applications, below 0.4microns, for example between about 0.1 microns and about 0.3 microns.Another embodiment of this invention is providing a method of producinga metaldehyde product where the d₅₀ is below 1 micron, preferably below0.7 microns, and for certain applications, below 0.4 microns, forexample between about 0.1 microns and about 0.3 microns. Anotherembodiment of this invention is providing a method of producing a zinebproduct where the d₅₀ is below 1 micron, preferably below 0.7 microns,and for certain applications, below 0.4 microns, for example betweenabout 0.1 microns and about 0.3 microns. Another embodiment of thisinvention is providing a method of producing a Ziram product where thed₅₀ is below 1 micron, preferably below 0.7 microns, and for certainapplications, below 0.4 microns, for example between about 0.1 micronsand about 0.3 microns. Another embodiment of this invention is providinga method of producing a Ferbam product where the d₅₀ is below 1 micron,preferably below 0.7 microns, and for certain applications, below 0.4microns, for example between about 0.1 microns and about 0.3 microns.Another embodiment of this invention is providing a method of producinga maneb product, a Mancozeb product, and a Maneb/Mancozeb product wherethe d₅₀ is below 1 micron, preferably below 0.7 microns, and for certainapplications, below 0.4 microns, for example between about 0.1 micronsand about 0.3 microns. Another embodiment of this invention is providinga method of producing a TPTH product where the d₅₀ is below 1 micron,preferably below 0.7 microns, and for certain applications, below 0.4microns, for example between about 0.1 microns and about 0.3 microns.

For foliar applications, the advantageously narrow particle sizedistribution is also provided by the method of producing a each of theabove products, where the d₉₀ is less than about 4 times the d₅₀,preferably less than three times the d₅₀; where the d₁₀ isadvantageously greater than about ¼th the d₅₀, preferably greater thanabout ⅓rd the d₅₀. Indeed, in the example the d₉₅ was of the milledchlorothalonil was within a factor of about 2 of the d₅₀.

One aspect of the invention relates to stable aqueous dispersions of theorganic biocide, e.g., chlorothalonil, that can be prepared by wetmilling an aqueous dispersion of the biocide in the presence of grindingmedia and a surface active agent, for use in foliar-type agriculturaltreatments, for example. For foliar treatment, the composition isgenerally combined with water to provide a stable suspension having thedesired concentration, and this stable suspension is then broadcast ontothe crops, as is known in the art.

In foliar applications, a smaller size particle is generally morepersistent than a larger size particle against degenerative/deactivatingforces such as rain. The preparation can be carried out in such a mannerso as to produce a dispersion of non-agglomerating or non-interactingparticles having a volume median diameter, d₅₀, of less than about 1micron and a d₉₀ of less than about 2 microns. In preferred embodiments,the preparation is carried out in such a manner so as to produce adispersion of non-agglomerating or non-interacting particles having avolume median diameter, d₅₀, of less than about 0.6 micron and a d₉₀ ofless than about 1.4 microns, preferably less than about 1 micron. Inother preferred embodiments, the preparation is carried out in such amanner so as to produce a dispersion of non-agglomerating ornon-interacting particles having a volume median diameter, d₅₀, of lessthan about 0.4 micron and a d₉₀ of less than about 1 micron, preferablyless than about 0.7 microns. For example, the method according to theinvention may advantageously produce a slurry where d₅₀ is between about0.1 and about 0.3 microns and where d₉₀ is less than about 3 times d₅₀.

Anti-Fouling Coating Applications—For anti-fouling paints and coatings,if there are combinations of particulate biocides, the size of theparticulates should be within a factor of about 5 of the size of theremaining particulates, though it is recognized that biocides withhigher solubility may require larger particles to have the desiredduration of effectiveness. One aspect of the invention relates to stableaqueous dispersions of the organic biocide, e.g., chlorothalonil, thatcan be prepared by wet milling an aqueous dispersion containing thebiocide in the presence of grinding media and a surface active agent,for use in anti-fouling paints and coatings, for example.

It is known to use 0.5 mm zirconia as a milling media for certainpigments to be used in paints. U.S. Published Patent Application No.2003/0127023 A1 teaches that pigments having improved colouristicproperties and process for their preparation, and describes exampleswhere compositions containing pigments and additives are milled with 0.5mm diameter zirconia milling media. In this publication, Irgaphor™ DPPRed B-CF (mean particle size about 50 nm, available from Ciba SpecialtyChemicals Inc) was admixed in a vessel with 8 mg Solsperse™ S22000(Zeneca); 32 mg Solsperse™ S24000 (Zeneca); 200 mg of a copolymer ofaromatic methacrylates and methacrylic acid (MW from 30,000 to 60,000);1.76 g of (1-methoxy-2-propyl)-acetate; and 5 g zirconia beads ofdiameter 0.5 mm. The vessel was sealed with an inner cup placed in anoperating paint conditioner for 3 hours, in order to yield a dispersion.The milled pigments forming the ingredients in this patent were all lessthan 0.2 microns in average diameter before milling, and most examplescontained pigments with average particle size less than 0.1 micronsbefore milling. This illustrates the advantage of this invention.Generally, it is known that pigments in paints form a more impermeablelayer if the particle size of the pigments is reduced. However, this hasnot been applied to the biocides—until now, there was no economical andreliable method of obtaining chlorothalonil, for example, at such asmall particle size. Now, our method allows a variety of biocidal agentsapproved for use in anti-fouling paints and coatings to be reliablymilled to provide both the desired sub-micron d₅₀ but also to providethe desired narrow particle size distribution, exemplified by d₉₀ (andpreferably d₉₅) being less than about twice the d₅₀.

Commonly used biocides in marine applications includes copper(I) oxide,copper thiocyanate, Cu powder, zinc oxide, chromium trioxide, Irgarol™1051, zinc pyrithione, dichlofluanid, TCMBT (2-(thiocyanomethylthio)benzothiazole, a liquid biocide), chlorothalonil,2,3,5,6-tetrachloro-4-sulfuronyl pyridine, SeaNine 211(4,5-dicholo-2-n-octyl-4-isothiazolin-3-one), ziram (zincdimethyldithiocarbamate or bis(dimethylcarbamodithioato-S,S′)zinc),zineb, folpet, and the like. Generally, the particles are held in placeby the paint or coating matrix. The sizes of the particulate biocidesare therefore primarily a function of the anticipated duration of thetreatment and the biocide dissolution rate, and are also a function ofthe desired particle size for the paint or coating. Finer particles makesmoother and less permeable coatings. The copper oxide, zinc oxide, andthe chlorothalonil are particularly suited for milling intosubmicron-sized particles using the procedures described herein, having,e.g., d₅₀ from about 0.1 to about 0.9 microns, and, e.g., a d₉₀ lessthan three times, preferably less than two times, the d₅₀ value. Forinstance, one example would be a composition with a d₅₀ of about 0.2microns and a d₉₀ of about 0.4 microns or less. Such small particles,when combined with adequate particle size distribution control, wouldprovide greater coverage, less permeability, and more gloss than waspreviously obtainable with formulations using larger particulates havinga wider size distribution.

The preparation is carried out in such a manner so as to produce adispersion of non-agglomerating or non-interacting particles having avolume median diameter, d₅₀, of less than about 1 micron and a d₉₀ ofless than about 2 microns. In preferred embodiments, the preparation iscarried out in such a manner so as to produce a dispersion ofnon-agglomerating or non-interacting particles having a volume mediandiameter, d₅₀, of less than about 0.6 microns and a d₉₀ of less thanabout 1.4 microns, preferably less than about 1 micron. In otherpreferred embodiments, the preparation is carried out in such a mannerso as to produce a dispersion of non-agglomerating or non-interactingparticles having a volume median diameter, d₅₀, of less than about 0.4micron and a d₉₀ of less than about 1 micron, preferably less than about0.7 microns. For example, the method according to the invention mayadvantageously produce a slurry where d₅₀ is between about 0.1 and about0.3 microns and where d₉₀ is less than about 3 times d₅₀.

Injectable Wood Preservative Applications—For wood treatments, theoverriding consideration is that the particles of each biocide, and ofthe combined biocides, be injectable into the wood matrix.

One aspect of the invention relates to stable aqueous dispersions of theorganic biocide, e.g., chlorothalonil, that can be prepared by wetmilling an aqueous dispersion of the biocide in the presence of grindingmedia and a surface active agent, for use as an injectable woodpreservative, for example. The injectable particulate organic biocidecan, for example, comprise chlorothalonil, metaldehyde, manganeseethylenebis(dithiocarbamate) (Maneb), salts thereof, or mixturesthereof.

Another aspect of the invention relates to wood or a wood productcomprising a milled biocide according to the invention and, optionally,one or more additional materials having a preservative function,injected into a piece of wood. The concurrent use of other organicbiocides, inorganic biocidal sparingly soluble salts and/or oxides, andliquid organic biocides coated onto the particulate biocides can beparticularly useful for treating wood, where combinations of biocidesare commonly used.

The requirements of injectability for substantially round/sphericalparticles (e.g., in which the diameter is one direction is within afactor of two of the diameter measured in an orthogonal direction)include, but are not limited to, the following: where d₉₈ is not morethan about 0.5 microns, preferably not more than about 0.3 microns, forexample not more than about 0.2 microns; and/or where the d₉₆,preferably the d₉₉, is less than about 1.5 microns, preferably less thanabout 1 micron, for example less than about 0.7 microns. The preparationis carried out in such a manner so as to produce a dispersion ofnon-agglomerating or non-interacting particles that meet the aboverequirements, and further having a volume median diameter, d₅₀, of lessthan about 0.4 microns and preferably a d₉₀ of less than about 0.7microns. Different wood materials require different particle sizes, butthe above ranges are generally sufficient for Southern Pine wood.

Milling is advantageously performed with the dispersants and surfaceactive agents. The slurry for injection into wood may comprise solublecopper such as aqueous copper monoethanolamine carbonate, or finelyground sparingly soluble copper salts, preferably copper hydroxide or abasic copper salt, e.g., preferably basic copper carbonate but alsooptionally including basic copper sulfate, basic copper phosphate, basiccopper nitrate, and the like. Advantageously the inorganic particulatessuch as the sparingly soluble copper salts have approximately the samed₅₀ as the ground organic biocide, e.g., within a factor of two orthree, and has similar limitations on the particle size distribution.Other components can be added, including other milled components—zincoxide provides complementary biocidal activity, copper(I) oxide providesvery low levels of biocidal activity but is extremely long lasting, andvarious iron oxide pigments can provide protection of wood very near thesurface from UV radiation. Any combination of these can be formed into aslurry which is readily injected into wood using standard industryprocedures, and is retained at levels generally well over 95%.

Its generally not advantageous to mill various components at the sametime—each component should be individually milled to its requiredspecifications, and then the slurry can be prepared to specification bymixing components. One exception may be where the organic biocide beingmilled is too plastic to obtain the desired particle size, in which caseit may be advantageous to add a quantity of small particulate, millablematerial with high porosity, such as alumina. Milling certain biocidesin combination with submicron alumina and with the required dispersantsmay allow particularly resistant biocides to be milled into a sizeamenable for injection into wood.

Other aspects of the present invention include methods for preparing theground biocide particulates according to the invention, methods offormulating injectable wood treatment compositions that comprise groundbiocide particulates, methods of transporting the injectable woodtreatments, methods of mixing and injecting the ground biocideparticulate composition according to the invention into wood and/or woodproducts, and also the wood and wood products themselves treated withthe ground biocide particulate compositions according to the invention.

In preferred embodiments, the preparation is carried out in such amanner so as to produce a dispersion of non-agglomerating ornon-interacting particles having a volume median diameter, d₅₀, of lessthan about 0.35 microns and a d₉₅ of less than about 0.7 microns,preferably less than about 0.5 microns. In other preferred embodiments,the preparation is carried out in such a manner so as to produce adispersion of non-agglomerating or non-interacting particles having avolume median diameter, d₅₀, of less than about 0.3 microns and a d₉₅ ofless than about 0.6 microns, preferably less than about 0.5 microns. Forexample, the method according to the invention may advantageouslyproduce a slurry where d₅₀ is between about 0.1 and about 0.3 micronsand where d₉₀ is less than about 3 times d₅₀. In one preferredembodiment, at least 80% by weight of the organic biocide particulateshave a size/diameter between about 0.05 microns and about 0.4 microns.

Injectability can and often does require that the particulates besubstantially free of the size and morphology that will tend toaccumulate and form a plug or filter cake, generally on or near thesurface of the wood, that results in undesirable accumulations on woodin one or more outer portions of the wood and thus a deficiency in aninner portion of the wood. Injectability is generally a function of thewood itself, as well as the particle size, particle morphology, particleconcentration, and the particle size distribution. We recognize that acompetitor may spike a composition with a small number of very largeparticles, in a quantity where the very large particles are not injectedbut are also not present in an amount which can impede usefulness of theproduct. In these cases, having very distinct bi-modal distributions ofparticles where the larger particles are not injectable, it isappropriate to ignore those very large particles when calculating theparticle size distributions. For example, a composition having about 90%of particles in the range of about 0.02 to about 0.5 microns will beinjectable into wood, if the remaining ˜10% has, for example, a particlediameter of at least about 5 microns, which size is so large that poreblocking may be reduced or the particle would even settle harmlessly tothe bottom of the tank.

The particulate organic biocides of this invention can be incorporatedinto wood composites, by either being mixed with binder, by coating woodfibers prior to binding, by being injected into wood chips prior tobinding, or any combination of the above. Again, a plurality ofadjuvants, including sparingly soluble biocidal salts, UV resistant ironoxide pigments, and the like can be milled and added to the wood chipsprior to forming the composite. Preferred wood composites have theground biocide according to this invention (and/or a compositioncontaining same) either mixed with the wood particles before bonding, orpreferably injected into the wood particulates and dried prior tobonding.

By “injectable,” we mean the ground biocide particulates are able to bepressure-injected into wood, wood products, and the like, to depthsnormally required in the industry, using equipment, pressures, exposuretimes, and procedures that are the same or that are substantiallysimilar to those currently used in industry. Pressure treatment is aprocess performed in a closed cylinder that is pressurized, forcing thechemicals into the wood. In preferred embodiments of the invention,incising is not expected to be required to inject the slurries of thepresent invention into lumber having thicknesses of about 6 to about 10inches. Wood or wood products comprising ground biocide particlesaccording to the invention may be prepared by subjecting the wood tovacuum and/or pressure in the presence of a flowable material comprisingthe ground biocide particles. A pre-injection of carbon dioxide followedby vacuum and then injection of a biocidal slurry is one preferredmethod of injecting the slurry into wood. Injection of particles intothe wood or wood product from a flowable material comprising theparticles may require longer pressure treatments than would be requiredfor liquids free of such particles. Pressures of, for example, at leastabout 75 psi, at least about 100 psi, or at least about 150 psi may beused. Exemplary flowable materials include liquids comprising groundbiocide particles, emulsions comprising ground biocide particles, andslurries comprising ground biocide particles.

In one embodiment, a volume number density of the ground biocideparticles according to the invention about 5 cm from the surface, andpreferably throughout the interior of the wood or wood product, is atleast about 50%, for example, at least about 60%, at least about 70%, orat least about 75% of the volume number density of the ground biocideparticles about 1 cm from the surface.

The requirements of injectability for substantially round/spherical,rigid particles (e.g., in which the diameter is one direction is withina factor of two of the diameter measured in an orthogonal direction)generally include, inter alia: 1) that substantially all the particles,e.g., greater than about 98% by weight, have a particle size withdiameter not more than about 0.5 microns, for example not more thanabout 0.3 microns or not more than about 0.2 microns; and 2) thatsubstantially no particles (e.g., less than about 0.5% by weight) have adiameter greater than about 1.5 microns, or an average diameter greaterthan about 1 micron, for example. We believe the first criterionprimarily addresses the phenomena of bridging and subsequent plugging ofpore throats, and the second criterion addresses the phenomena offorming a plug, or filter cake. Once a pore throat is partially plugged,complete plugging and undesired buildup generally quickly ensues.

In one embodiment, the size distribution of the injectable particlesrequires that the vast majority of particles (for example at least about95% by weight, preferably at least about 99% by weight, more preferablyat least about 99.5% by weight) be of an average diameter less thanabout 1 micron. Advantageously, the particles are not too elongated, orrod-shaped, with a single long dimension. Average particle diameter isbeneficially determined by Stokes Law settling velocities of particlesin a fluid to a size down to about 0.2 microns. Smaller sizes arebeneficially determined by for example a dynamic light scattering methodor laser scattering method or electron microscopy. Generally, such aparticle size and particle size distribution can be achieved bymechanical attrition of particles.

Attrition can be obtained by wet milling in a sand grinder charged with,for example, partially stabilized zirconia beads with a diameter ofabout 0.5 mm; alternatively wet milling in a rotary sand grinder withpartially stabilized zirconia beads with a diameter of about 0.5 mm andwith stirring at, for example, about 1000 rpm or more; or by use of awet-ball mill, an attritor (e.g., manufactured by Mitsui Mining Ltd.), apearl mill (e.g., manufactured by Ashizawa Ltd.), or the like. Attritioncan be achieved to a lesser degree by centrifugation, but largerparticles can be simply removed from the composition via centrifugation.Removing the larger particulates from a composition can provide aninjectable formulation. Said particulates can be removed bycentrifugation, where settling velocity substantially follows Stokeslaw.

The most effective method of modifying the particle size distribution iswet milling. Beneficially all injectable formulations for wood treatmentshould be wet-milled, even when the “mean particle size” is well withinthe range considered to be “injectable” into wood. Even when a fewweight percent of particles exhibit a size above about 1 micron, thissmall amount of material is hypothesized to form the start of a plug(where smaller, normally injectable particles are subsequently caught bythe plug). Further, it is believed that wet milling with larger-sizedmedia (e.g., 2 mm zirconium silicate) will have virtually no effect,resulting in only a marginal decrease in particle size, such that thematerial will still not be injectable in commercial quantities.

However, it has been found that a milling process using about 0.5 mmhigh density zirconium-containing (e.g., preferably zirconium oxide)grinding media provides efficient attrition, especially for the removalof particles greater than about 1 micron in the commercially availablebiocide particulate product. The milling process usually takes on theorder of minutes to achieve almost complete removal of particles greaterthan about 1 micron in size. As stated above, the size of the millingmaterial is believed to be important, even critical, to obtaining acommercially acceptable process. The milling agent material having adiameter of about 1 or 2 mm (or greater) are ineffective, while millingagent material having a diameter of about 0.5 mm is effective typicallyafter about 15 to 120 minutes of milling.

EXAMPLES

The following examples are merely indicative of the nature of thepresent invention, and should not be construed as limiting the scope ofthe invention, nor of the appended claims, in any manner.

Example 1 Milling Chlorothalonil with 0.5 mm Zirconium Silicate

The laboratory-sized vertical mill was provided by C B Mills, model#L-3-J. The mill has a 2 liter capacity and is jacketed for cooling.Unless otherwise specified, ambient water was cycled through the millcooling jacket during operation. The internal dimensions are 3.9″diameter by 9.1″ height. The mill uses a standard 3×3″ disk agitator(mild steel) on a stainless steel shaft, and it operates at 2,620 rpm.

The media used in this Example was 0.4-0.5 mm zirconium silicate beadssupplied by C B Mills. All particle size determinations were made with aSedigraph™ 5100T manufactured by Micromeritics, which uses x-raydetection and bases calculations of size on Stokes' Law.

The formulation contained 20.41% chlorothalonil (98% active), 5%Galoryl™ DT-120, 2% Morwet™ EFW, and 72.6% water by weight, and theconcentrate had a pH of 8.0. The total batch weight was about 600 g. Theresults of a 7.5 hour grinding study are given in Table 1 below.

TABLE 1 Milling Particle Size Data - Volume % Time d₅₀ With DiameterGreater Than Mins. μm 10 μm 5 μm 2 μm 1 μm 0 4.9 10 48 95 30 1.3 0 4 2168 60 1.0 4 2 11 50 90 1.4 18 23 22 94 120 1.03 2 0 4 150 1.12 0 2 6 58180 1.07 2 2 7 53 270 1.09 2 0 8 54 450 1.15 12 8 21 56

The results show that chlorothalonil can be wet milled from a startingparticle size of about 3-4 microns to a d₅₀ near 1 micron within aboutone hour, using a spherical ˜3.8 g/cm³ zirconium silicate media havingan average particle size of about 0.4-0.5 mm. Further grinding hadlittle effect, possibly slightly reducing the weight of particles overabout 2 microns and thereby reducing the d₅₀ from about 2 microns at 60minutes to slightly less than 2.

However, these results also showed the limitations of this lower densitymaterial. In the next example, higher density doped zirconia, having adensity of 5.5 to 6.5 g/cc, was used and provided much more effectivemilling.

Example 2 Milling Chlorothalonil with 0.5 mm Zirconium Oxide

The same mill and conditions were used in this experiment as inexperiment 1. However, the grinding media was 0.5-0.6 mm cerium-dopedzirconium oxide beads obtained from CB Mills. The density of the ceriumdoped zirconium oxide is ˜6.0 g/cm³. The formulation contained 20.41%chlorothalonil (98% Active), 5% Galoryl™ DT-120, 2% Morwet™ EFW, 3%Pluronic™ F-108, and 69.6% water by weight, and the concentrate had a pHof about 7.3. The total batch weight was about 600 g. The results areshown in Table 2 below.

TABLE 2 Milling Particle Size Data - Volume % Time d₅₀ With DiameterGreater Than Mins. μm 10 μm 5 μm 2 μm 1 μm 0.4 μm 0.2 μm 0 3.44 8 30 7792 — — 90 0.31 3 3 3 3 22 — 240 0.21 0 1 2 3 3 51

For the higher density 0.5 mm zirconia milling media, a composition witha d₅₀ less than 1 micron and a d₉₅ less than 1 micron was obtainable in90 minutes, and a composition with a d₅₀ less than 0.3 microns and a d₉₅less than 0.4 microns was obtainable in 6 hours. The product obtainedafter 90 minutes of milling represents an increase in number ofparticles per unit of mass by a factor of more than about 30 over thestandard products, but the product obtained after 90 minutes of millingrepresents an increase in number of particles per unit of mass by afactor of more than about 1000 over the standard products. The highersurface areas associated with the smaller particles should give rise toa product with enhanced bioactivity due to an increase in reservoiractivity (ability to deliver chlorothalonil to the infection court).

Example 3 Milling Sparingly Soluble Copper Salts with 0.5 mm ZirconiumSilicate

This comparative example and subsequent example show the effectivenessof the milling media and process on the particle size distribution ofinorganic copper salts.

Comparative Example 3A

A commercially available a magnesium stabilized form of copper hydroxideparticulate material, Champ DP® available from available fromPhibro-Tech., Inc., has particles with a d₅₀ of about 0.2 microns. FIG.3 shows the results of trying to inject untreated 2.5 micron d₅₀ copperhydroxide into wood. The copper material plugged the surface of the woodand made an unsightly blue-green stain. The results were less dramaticwhen injecting Champ DP, but were still commercially unacceptable.Analysis of the material found that while the d50 of the material was<0.2 microns, about 13% by weight of the material had diameters between2 and 5 times greater than the d₅₀, and 1% had an even greater diameter.

The Champ DP® material was placed in a mill with about a 50% by volumeloading of 2 mm zirconium silicate milling beads. Samples were removedintermittently and the particle size distribution was determined. Wetmilling with 2 mm zirconium silicate milling media had no effect—wetmilling for days resulted in only a very slight decrease in particlesize, a small shift in the particle size distribution, but the materialwas not injectable into wood

In contrast, five samples of particulate copper salts made followingstandard procedures known in the art were milled according to the methodof this invention. The first two samples were copper hydroxide—one withan initial particle size d₅₀ of <0.2 microns (the material ofcomparative example A), and the second with an initial d₅₀ of 2.5microns. A basic copper carbonate (BCC) salt was prepared and it had aninitial d₅₀ of 3.4 microns. A tribasic copper sulfate salt was preparedand this material has a d₅₀ of 6.2 micron. Finally, a copper oxychloride(COc) sample was prepared and this material has an initial d₅₀ of 3.3microns. Selected surface active agents were added to each slurry, andthe initial slurries were each in turn loaded into a ball mill having0.5 mm zirconium silicate (density 3.8 grams/cm³) at about 50% of millvolume, and milled at about 2600 rpm for about a half an hour. Theparticle size distribution of the milled material was then determined.The particle size distribution data is shown in Table 1. It can be seenthat even with the relatively modest zirconium silicate milling media,injectable compositions were obtained in about 30 minutes milling timeor less.

TABLE 1 Particle Size Distribution Before/After Milling (0.5 mmZirconium Silicate) Material d50 % < 10μ % < 1μ % < 0.4μ % < 0.2μCu(OH)₂, before <0.2 99% 84% 64% 57% milling Cu(OH)₂, after <0.2 99% 97%95% 85% milling Cu(OH)2, before 2.5 99%  9% — — milling Cu(OH)2, after0.3 99.7%   95% 22% —% milling BCC*, before 3.4 98% 1.2%  — — millingBCC*, after <0.2 99% 97% 97% 87% milling TBS*, before 6.2 70% 17% — —milling TBS*, after <0.2 99.5%   96% 91% 55% milling COc*, before 3.398.5%    3% — — milling COc*, after 0.38 99.4%   94% 63% — milling

It can be seen that even the less effective milling media, ˜0.5 mmzirconium silicate, was useful for milling sparingly soluble coppersalts to the sub-micron particle size distribution needed for treatingwood, for incorporating into non-fouling paints and coatings, and forfoliar treatments. Further, the rate of particle size attrition is sogreat that there is no need to use expensive precipitation techniques toprovide a feedstock having a sub-micron d₅₀. The initial d50 ranged from0.2 microns to over 6 microns, but after 30 minutes or less of millingeach of the above milled copper salts (milling about 15 to about 30minutes) were injected into wood samples with no discernible plugging.

Milling with the more preferred zirconium oxide milling beads willprovide a smaller d50 and will further reduce the amount of material, ifany, having a diameter greater than 1 micron. Particulate biocides havean advantage over dispersed or soluble biocides in that the materialleaches more slowly from wood than would comparable amounts of solublebiocides, and also about the same or more slowly than comparable amountsof the same biocide applied to the same wood as an emulsion.

Example 4 Injecting Milled Copper Salt Slurries into Wood

Slurries of the above milled sparingly soluble copper salts weresuccessfully injected into standard 1″ cubes of Southern Yellow Pinewood. The injection procedures emulated standard conditions used in theindustry.

FIG. 3 shows representative photographs showing the comparison of theunacceptable product, which had a d₅₀ of 2.5 microns and completelyplugged the wood, is shown in comparison with blocks injected with theproduct milled according to the process of this invention as describedin Example 3. FIG. 3 shows the clean appearance of the wood blocksinjected with the milled copper hydroxide, to compare with thephotograph of the wood samples injected with the un-milled (d₅₀<0.2micron) copper hydroxide. Unlike the blocks injected with un-milledmaterial, wood blocks injected with milled material showed little or nocolor or evidence of injection of copper-containing particulate salts.

Copper development by colorimetric agents (dithio-oxamide/ammonia)showed the copper to be fully penetrated across the block in the sapwoodportion. FIG. 1 shows the penetration of injected particulate copperhydroxide developed with dithio-oxamide in the third picture. The staincorresponds to copper. It can be seen in FIG. 1 that the copper isevenly dispersed throughout the wood. Subsequent acid leaching andquantitative analysis of the copper from two blocks showed that loadingsof about 95% and about 104% of expectation (or essentially 100% averageof expectation) had occurred. At 100% loading, values of 0.22 lb/ft³ ofcopper would be obtained.

Example 5 Leaching Copper from Treated Wood

Copper leaching rates from the wood samples prepared in Example 4 weremeasured following the AWPA Standard Method E11-97. There are twocomparative examples—leaching data was obtained from a wood blockpreserved with a prior art soluble solution of copper MEA carbonate andfrom a prior art wood block preserved with CCA. The leach rates of thevarious wood blocks treated with the preservatives prepared according tothis invention were far below the leach rates of wood treated withsoluble copper carbonate and were even below leach rates of samplestreated with CCA.

Leaching data from wood was measured following the AWPA Standard MethodE11-97 for the following preservative treatments, where, unlessspecified, the tebuconazole (TEB) concentration was added as an emulsionat 3% of the weight of the added copper: A) TEB and injected basiccopper carbonate particulates; B) traditionally CCA-treated wood (as acontrol); C) TEB and copper methanolamine carbonate (as a control,believed to approximate the currently available Wolman E treatment); D)TEB and injected basic copper carbonate particulates and with sodiumbicarbonate buffer; E) Injected basic copper carbonate particulates; F)TEB and injected copper hydroxide particulates modified with zinc andmagnesium; G) about 5% TEB and injected copper hydroxide particulatesmodified with phosphate coating; H) TEB and injected tribasic coppersulfate particulates; and I) TEB and injected copper oxychlorideparticulates. The leaching data for the various particulate slurries andfrom two controls are shown in FIG. 2.

The total copper leached from wood preserved with copper-MEA-carbonatewas 5.7% at 6 hours, 8.5% at 24 hours, 11% at 48 hours, 22% at 96 hours,36% at 144 hours, 49% at 192 hours, 62% at 240 hours, 69% at 288 hours,and 76% at 336 hours. The amount of copper leached from copper hydroxideparticulates was 0.4% at 6 hours, 0.6% at 24 hours, 0.62% at 48 hours,1.0% at 96 hours, 1.6% at 144 hours, 2.1% at 192 hours, 3.2% at 240hours, 3.4% at 288 hours, and 3.7% at 336 hours. The difference in leachrate was greater than a factor of 20.

The leaching data is generally consistent within the small amount ofcopper leached from these wood samples. Using the copper leach rate ofCCA as a standard, and viewing the total leached copper at 96 and 240hours as representative, the leach rate ratios given by the “totalleached copper to total CCA-leached copper” is given in Table 3 below.

Of the sparingly soluble salts used, the leach rate, in descendingorder, is as follows: copper MEA carbonate (comparative)>>copperoxychloride>tribasic copper sulfate and/or copper hydroxide withphosphate>basic copper carbonate>copper hydroxide with Zn and Mg. Theisoelectric point of copper oxychloride is about 5 to about 5.5, and theisoelectric point of tribasic copper sulfate is about 6 to about 6.5. Asthese materials are very poor bases, the higher leach rates from thematerials is consistent with expected higher solubility at lower pHvalues. The presence of TEB reduced leach rates from basic coppercarbonate by about 20%, most likely due to TEB partially coatingparticulates. A buffering system, sodium bicarbonate, reduced the leachrates from TEB/basic copper carbonate by about 10% relative to apreservative without the buffer.

TABLE 3 96 hr. ratio 240 hr. ratio Ex. Description of PreservativeSystem to CCA to CCA A 3% TEB and basic copper carbonate particulates0.67:1 0.51:1 C 3% TEB and copper MEA carbonate (comparative)  5.2:13.85:1 D 3% TEB and basic copper carbonate particulates with 0.54:10.46:1 sodium bicarbonate buffer E basic copper carbonate particulates0.77:1 0.63:1 F 3% TEB and copper hydroxide with Zn and Mg  0.2:1 0.19:1particulates G 5% TEB and copper hydroxide particulates modified  1.0:10.88:1 with phosphate coating H 3% TEB and tribasic copper sulfateparticulates 0.96:1 0.88:1 I 3% TEB and copper oxychloride particulates 1.4:1 1.17:1

Use of the small diameter milling material, preferably 0.3 mm to 0.6 mm,is essential to make a product that can be confidently sold forinjection into wood.

Example 5 Toxicity Evaluation

A sample of treated wood was sent to an outside source forshort-duration toxicity testing. The results suggest there is nodifference in the Threshold Toxicity between wood treated with a copperMEA carbonate/tebuconazole formulation and wood treated with a identicalloading of basic copper carbonate particles of this invention admixed(and partially coated with) the same quantity of tebuconazole.

The invention is meant to be illustrated by these examples, but notlimited to these examples.

1: A method of preparing a particulate organic biocide productcomprising the steps of: 1) providing an solid substantiallywater-insoluble organic biocide, an aqueous liquid comprising asurface-active agent, and a milling media to a mill, wherein the millingmedia comprises an effective amount of milling beads having a density ofabout 3.5 grams/cm³ or greater, and a diameter between about 0.1 mm andabout 0.8 mm; and 2) milling the material for a time sufficient toobtain a milled organic biocide product having a mean volume particlediameter d₅₀ of about 0.05 microns to about 1 micron. 2: The method ofclaim 1 wherein the milling media comprises an effective amount ofmilling beads comprising zirconia and having a density or about 5.5grams/cm³ or greater. 3: The method of claim 1 wherein 10% or more byweight of the milling media comprises zirconium oxide-containing millingbeads having a diameter between about 0.1 and about 0.7 mm. 4.(canceled) 5: The method of claim 4 wherein the milled organic biocideproduct has a diameter d₉₀, such that 90 volume percent of the producthas a diameter of the d₉₀ or less, of less than 4 times the d₅₀. 6-7.(canceled) 8: The method of claim 3 wherein the product has a meanvolume particle diameter d₅₀ of between about 0.1 microns and about 0.3microns. 9-11. (canceled) 12: The method of claim 1 wherein at least 25%by weight of the milling media consists of milling beads having adiameter between about 0.1 mm and about 0.8 mm which consist essentiallyof zirconium oxide, doped zirconium oxide, stabilized zirconium oxide,or mixture thereof. 13: The method of claim 1 wherein at least 5% byweight of the milling media consists of milling beads having a diameterbetween about 0.2 mm and about 0.7 mm and a density greater than about5.5 grams per cubic centimeter. 14-16. (canceled) 17: The method ofclaim 3 wherein the milling media consists essentially of milling beadshaving a diameter between about 0.3 and about 0.7 mm and a density of5.5 g cc or greater, and wherein the milling media occupies betweenabout 40 and 80 volume % of the mill. 18: The method of claim 16 whereinthe mill speed is between about 1000 and about 4000 rpm. 19: The methodof claim 1 wherein at least 10% by weight of the milling media consistsof steel milling beads having a diameter between about 0.2 and about 0.7mm and a density of 6 g/cc or greater.
 20. (canceled) 21: The method ofclaim 1 wherein the milling media comprises steel. 22-30. (canceled) 31:The method of claim 1 wherein the organic biocide is selected from thegroup consisting of Metaldehyde, triphenyltin hydroxide, Maneb,Mancozeb, Zineb, Ziram, and Ferbam, and wherein the milled organicbiocide product has a volume mean diameter d₅₀ between about 0.1 and 0.3microns and a d₉₀, such that 90 volume percent of the product has adiameter of the d₉₀ or less, of less than about 3 times the d₅₀. 32-33.(canceled) 34: A method of treating crops comprising: milling an organicbiocide product according to claim 28, wherein the milled organicbiocide product further comprises the surface active agents; adding themilled organic biocide product to water to form slurry; and spraying theslurry over the crops.
 35. (canceled) 36: The method of claim 1 whereinthe organic biocide is selected from the group consisting ofimidazolinones, sulfonylureas, triazolopyrimidine sulfonamides,aryloxyphenoxy propionates, triazines, chloroacetanilides, pyrazoles,and diphenyl ethers. 37-39. (canceled) 40: A method of treating cropscomprising: milling an organic biocide product according to claim 36,wherein the milled organic biocide product further comprises the surfaceactive agents; adding the milled organic biocide product to water toform slurry; and spraying the slurry over the crops. 41: The method ofclaim 1 wherein the organic biocide is selected from the groupconsisting of amitraz, azinphos-ethyl, azinphos-methyl, benzoximate,fenobucarb, gamma-HCH, methidathion, deltamethrin, dicofol,dioxabenzafos, dioxacarb, dinobuton, endosulfan, bifenthrin, binapacryl,bioresmethrin, chlorpyrifos, chlorpyrifos-methyl, EPNethiofencarb,cyanophos, cyfluthrin, tetradifon, cypermethrin, tralomethrin,bromophos, N-2,3-dihydro-3-methyl-1,3-thiazol-2-ylidene-xylidene,2,4-parathion methyl, bromopropylate, butacarboxim, butoxycarboxin,chlordimeform, phosalone, chlorobenzilate, phosfolan, chloropropylate,phosmet, chlorophoxim, promecarb, fenamiphos, quinalphos, resmethrin,temephos, pirimiphos-ethyl, tetramethrin, pirimiphos-methyl, xylylcarb,profenofos, acrinathrin, propaphos, allethrin, propargite, benfuracarb,propetamphos, bioallethrin, pyrachlofos, bioallethrin S, tefluthrin,bioresmethrin, terbufos, buprofezin, tetrachlorinphos, chlorfenvinphos,tralomethrin, chlorflurazuron, triazophos, chlormephos, pyrachlofos,tefluthrin, terbufos, tetrachlorinphos, cycloprothrin, betacyfluthrin,cyhalothrin, cambda-cyhalothrin, tralomethrin, alpha-cypermethrin,triazophos, beta-cypermethrin, cyphenothrin, demeton-5-methyl,dichlorvos, disulfoton, edifenphos, empenthrin, esfenvalerate,ethoprophos, etofenprox, etrimphos, fenazaquin, fenitrothion,fenthiocarb, fenpropathrin, fenthion, fenvalerate, flucythrinate,flufenoxuron, tau-fluvalinate, formothion, hexaflumuron, hydroprene,isofenphos, isoprocarb, isoxathion, malathion, mephospholan, methoprene,methoxychlor, mevinphos, permethrin, phenothrin, phenthoate, benalaxyl,biteranol, bupirimate, cyproconazole, carboxin, tetraconazole,dodemorph, difenoconazole, dodine, dimethomoph, fenarimol, diniconazole,ditalimfos, ethoxyquin, myclobutanil, etridiazole, nuarimol,fenpropidin, oxycarboxin, fluchloralin, penconazole, flusilazole,prochloraz, imibenconazole, tolclofos-methyl, myclobutanil, triadimefon,propiconazole, triadimenol, pyrifenox, azaconazole, tebuconazole,epoxyconazole, tridemorph, fenpropimorph, triflumizole, 2,4-D esters,diclofop-methyldiethatyl, 2,4-DB esters, dimethachlor, acetochlor,dinitramine, aclonifen, ethalfluralin, alachlor, ethofumesate,anilophos, fenobucarb, benfluralin, fenoxapropethyl, benfuresate,fluazifop, bensulide, fluazifop-P, benzoylprop-ethyl, fluchloralin,bifenox, flufenoxim, bromoxynil esters, flumetralin, bromoxynil,flumetralin, butachlor, fluorodifen, butamifos, fluoroglycofen ethyl,butralin, fluoroxypyr esters, butylate, carbetamide, chlornitrofen,chlorpropham, cinmethylin, clethodim, clomazone, clopyralid esters, CMPPesters, cycloate, cycloxydim, desmedipham, dichlorprop esters, flurecolbutyl, fluorochloralin, haloxyfop, ethoxyethyl, haloxyfop-methyl,ioxynil esters, isopropalin, MCPA esters, mecoprop-P esters,metolachlor, monalide, napropamide, nitrofen, oxadiazon, oxyfluorfen,pendimethalin, phenisopham, phenmedipham, picloram esters, pretilachlor,profluralin, propachlor, propanil, propaquizafop, pyridate,quizalofop-P, triclopyr esters, and tridiphane. 42: The method of claim41 wherein the milled organic biocide product has a volume mean diameterd₅₀ between about 0.1 and 0.3 microns and a d₉₀, such that 90 volumepercent of the product has a diameter of the d₉₀ or less, of less thanabout 3 times the d₅₀. 43-44. (canceled) 45: A method of treating cropscomprising: milling an organic biocide product according to claim 41,wherein the milled organic biocide product further comprises the surfaceactive agents; adding the milled organic biocide product to water toform slurry; and spraying the slurry over the crops. 46-54. (canceled)